Aromatic compounds

Abstract

The present invention relates to a compound of formula I R 1 ‑(A 1 ‑Z 1 ) r ‑B 1 ‑Z L ‑A 2 ‑(Z 3 ‑A 3 ) s ‑G(I), wherein the groups and parameters appearing therein have the meanings given in claim 1, and the present invention relates to its use for forming a molecular layer, in particular a self-assembled monolayer, to a method for making a switching element for a memristive device comprising the molecular layer, and to a memristive device comprising the switching element.

Description

[0001] The present invention relates to aromatic compounds, to their use in forming molecular layers, in particular self-assembled monolayers (SAMs), to a method for making a switching element for a memristive device comprising the molecular layer, and to a memristive device comprising the switching element.

[0002] In computer technology, there is a need for storage media that allow fast write and read access to the information stored therein. Solid-state memory or semiconductor memory enables particularly fast and reliable storage media, since no moving parts are required at all. Currently, dynamic random access memory (DRAM) is mainly used. DRAM allows fast access to stored information, but this information must be updated regularly, which means that when the power supply is cut off, the stored information is lost.

[0003] The prior art also discloses non-volatile semiconductor memories, such as flash memory or magnetoresistive random access memory (MRAM), in which information is retained even after the power supply is cut off. One disadvantage of flash memory is that write access is slow and the memory cells of flash memory cannot be erased indefinitely. The life of flash memory is usually limited to a maximum of one million read / write cycles. MRAM can be used in a similar manner to DRAM and has a long life, but this type of memory has not yet established itself due to the difficult production process.

[0004] Another alternative is a memory that works on the basis of a memristor. The term memristor is an abbreviation of the words "memory" and "resistor" and refers to a component that can reproducibly change its resistance between high resistance and low resistance. Even without a supplied voltage, the corresponding state (high resistance or low resistance) is maintained, meaning that a non-volatile memory can be realized with a memristor.

[0005] WO 2012 / 127542 A1 and US 2014 / 008601 A1, for example, disclose organic molecular memories having two electrodes and an active region arranged between the two electrodes. The active region has a molecular layer of an electrically conductive aromatic alkyne, the electrical conductivity of which can be changed under the influence of an electric field. A similar component based on redox-active bipyridinium compounds is proposed in US 2005 / 0099209 A1.

[0006] Known memories based on a change in conductivity or resistance have the disadvantage that free radical intermediates formed by the flow of current through the molecules in the molecular layer are in principle susceptible to degradation processes, which have a negative effect on the service life of the component.

[0007] In WO 2018 / 007337 A2, an improved switching layer is described which utilizes a non-redox-active molecular layer comprising a dipolar compound connected to a substrate via an aliphatic spacer, wherein the compound is reversibly switched by applying an electric field which causes a reorientation of the molecular dipoles, thereby enabling a low-resistance state and a high-resistance state to be achieved depending on the respective orientation of the molecules.

[0008] In order to obtain electrically switchable tunnel junctions from organic compounds with conformationally flexible dipoles, a molecular layer needs to be formed as a sandwich between two conducting electrodes. The deposition of this molecular layer on the electrodes can be achieved by spin coating or dip coating from an organic solvent. The basic principle of the resulting memory device is described in WO 2016 / 110301 A1 and WO 2018 / 007337 A2. In order to limit the formation of short circuits between top and bottom electrodes, the monolayer must be as compact as possible, with no pinholes that would allow penetration of top electrode material during the deposition process. There is also a strong demand for materials that form molecular layers of acceptable quality within extremely short deposition times.

[0009] The problem to be solved by the present invention is to provide improved materials for making switchable molecular layers.

[0010] In order to solve this problem, a compound of formula I shown below is provided, which comprises a ring having an anchor group connected to a polar ring via a single atom linking group, wherein the compound of formula I can be bound to a substrate via the anchor group.

[0011] The invention further relates to a method for producing a switching element comprising a molecular layer obtainable from one or more compounds of formula I. The invention further relates to a memristive device comprising the switching element.

[0012] Preferred embodiments are the subject matter of the dependent claims and can also be taken from the description.

[0013] The present invention relates to compounds of formula I

[0014] R 1 -(A 1 -Z 1 ) r -B 1 -Z L -A 2 -(Z 3 -A 3 ) s -G (I)

[0015] in

[0016] R 1represents a straight-chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, wherein one or more CH2 radicals in these radicals can each independently be replaced by -C≡C-, -CH=CH-, -O-, -S-, -CF2O-, -OCF2-, -CO-O-, -O-CO-, -SiR 0 R 00 -、-NH-、-NR 0 - or -SO2- is replaced in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen, CN, SCN or SF5, or,

[0017] R 1 Represents the group Dia-Z D ,

[0018] Dia represents a diamondoid radical, preferably derived from lower adamantane, very preferably selected from the group consisting of adamantyl, diadamantyl, triadamantyl, in which one or more H atoms may be replaced by an alkyl or alkoxy radical having up to 12 C atoms, in particular

[0019]

[0020] Z D With Z 1 and Z 3 One of the meanings of or represents a spacer group,

[0021] Z 1 , Z 3 represents, identically or differently on each occurrence, a single bond, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CH2O-, -OCH2-, -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -(CH2) n1 -、-(CF2) n2 -, -CF2-CH2-, -CH2-CF2-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH2) n3 O-, -O(CH2) n4 -, -C≡C-, -O-, -S-, -CH=N-, -N=CH-, -N=N-, -N=N(O)-, -N(O)=N- or -N=CC=N-,

[0022] n1, n2, n3, n4 are identical or different and are 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10,

[0023] Z LIndicates -O-, -S-, -CH2-, -C(O)-, -CF2-, -CHF-, -C(R x )2-、-S(O)-、-SO2-,

[0024] R 0 , R 00 represent, identically or differently, alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, moreover, one or more H atoms may be replaced by halogen,

[0025] R x represents a straight-chain or branched alkyl radical having 1 to 6 C atoms,

[0026] A 1 , A 3 represents, identically or differently on each occurrence, an aromatic, heteroaromatic, cycloaliphatic or heteroaliphatic ring having 4 to 25 ring atoms, which may also contain fused rings and which may be mono- or polysubstituted by Y,

[0027] A 2 represents an aromatic or heteroaromatic ring having 5 to 25 ring atoms, which may also contain fused rings and which may be mono- or polysubstituted by Y,

[0028] Y, identically or differently on each occurrence, represents F, Cl, CN, SCN, SF5 or linear or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, or cycloalkyl or alkylcycloalkyl having in each case 3 to 12 C atoms, preferably methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, trifluoromethyl, methoxy or trifluoromethoxy,

[0029] B 1 express

[0030]

[0031]

[0032] These groups can be oriented in two directions,

[0033] L 1 To L 5 independently represent F, Cl, Br, I, CN, SF5, CF3 or OCF3, preferably Cl or F, wherein L 3 Alternatively, H can be represented as

[0034] G represents -CH=CH2, -OH, -CH(CH2OH)2, -C(CH2OH)3, -B(OH)2, -SH, -SO2OH, -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2, -COOH, -Si(OR x )3 or -SiCl3, -SO2OR V 、-OP(O)(OR V )2.-PO(OR V )2、-C(OH)(PO(OR V )2)2, -COOR V 、-Si(OR V )3,

[0035] R V represents an alkyl group having 1 to 20 C atoms, preferably a secondary or tertiary alkyl group having 3 to 10 C atoms,

[0036] r is 0, 1, or 2, and

[0037] s is 0, 1, or 2,

[0038] Where r+s≤4.

[0039] The compounds of formula I are notable for their excellent solubility in polar aprotic solvents, such as ethyl acetate, 1-methoxy-2-propanol acetate, acetone, ethyl methyl ketone, cyclohexanone, and the like.

[0040] Furthermore, it enables rapid molecular layer formation, fast dip-coating process times, and high-quality monolayers deposited by spin-coating.

[0041] The molecular layers obtained from compounds of formula I are notable for dense packing and advantageously low water contact angles, enabling the fabrication of switching elements for memristive devices that can be patterned by photolithography using standard industrial processes. In addition, these monolayers have an extremely high thermal stability even at temperatures above 300°C.

[0042] Switching devices comprising molecular layers obtained from compounds of formula I show advantageously high current densities. Description of the drawings:

[0044] Attached picture shows

[0045] Figure 1 Schematic diagram of the layer structure of a memristive memory element.

[0046] Figure 2 An exemplary logarithmic plot of measured current density values ​​versus applied voltage in an exemplary embodiment of a memory device having a resistive switching memory element,

[0047] Figure 3 Exemplary logarithmic plots of measured current density values ​​versus applied voltage for a resistive switching memory element.

[0048] The term "adamantanes" refers to substituted and unsubstituted cage compounds of the adamantane series, including adamantane, diamantane, triamantane, tetraamantane, pentamantane, hexamantane, heptamantane, octamantane, etc., including all isomers and stereoisomers thereof. The compounds have an "adamantanes" topology, which means that their carbon atoms are arranged superimposed on a fragment of a face-centered cubic diamond lattice. The substituted adamantane from the first part of the series preferably has 1 to 4 independently selected alkyl or alkoxy substituents.

[0049] As such terms are defined herein, adamantane includes "lower adamantane" and "higher adamantane", as well as mixtures of any combination of lower and higher adamantane. The term "lower adamantane" refers to adamantane, diamantane and triamantane, and any and / or all unsubstituted and substituted derivatives of adamantane, diamantane and triamantane.

[0050] These lower adamantane components show no isomers or chirality and are easy to synthesize, which are different from "higher adamantanes". The term "higher adamantane" refers to any and / or all substituted and unsubstituted tetramantane components; any and / or all substituted and unsubstituted pentamantane components; any and / or all substituted and unsubstituted hexamantane components; any and / or all substituted and unsubstituted heptamantane components; any and / or all substituted and unsubstituted octamantane components; and mixtures of the above and isomers and stereoisomers of tetramantane, pentamantane, hexamantane, heptamantane and octamantane. Adamantane chemistry has been reviewed by Fort, Jr. et al. in "Adamantane: Consequences of the Diamondoid Structure," Chem. Rev. Vol. 64, pp. 277-300 (1964). Adamantane is the smallest member of the adamantane series and can be regarded as a single cage crystallographic subunit. Diamantane contains two subunits, triamantane contains three subunits, tetraamantane contains four subunits, and so on. While adamantane, diamantane, and triamantane exist in only one isomeric form, tetraamantane exists in four different isomers (two of which represent mirror-image pairs), i.e., four different possible arrangements of the four adamantane subunits. The number of possible isomers increases nonlinearly with each higher member of the adamantane series, pentamantane, hexamantane, heptamantane, octamantane, etc.

[0051] As used herein, an anchoring group is a functional group by which a compound is adsorbed or bound to a substrate surface by physical adsorption, chemical adsorption or by chemical reaction.

[0052] A spacer group in the sense of the invention is a flexible chain between two rigid groups which brings about a separation between these substructures and, due to its flexibility, at the same time improves the mobility of at least one of these groups after binding to the substrate.

[0053] If Z D represents a spacer group, the group is preferably selected from the formula Sp'-X', so that the group Dia-Z of formula I D - corresponds to the formula Dia-Sp'-X'-, wherein

[0054] Sp' denotes a straight-chain or branched alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein, in addition, one or more non-adjacent CH2 groups may each be independently substituted by -O-, -S-, -NH-, -NR 0 -、-SiR 00 R 000 -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR 0 -CO-O-, -O-CO-NR 0 -、-NR 0 -CO-NR 0 -, -CH=CH- or -C≡C- are replaced in such a way that O and / or S atoms are not directly connected to each other,

[0055] X' represents -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 00 -、-NR 00 -CO-、-NR 00 -CO-NR 00 -, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 00 -、-CY x =CY x‘ -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH- or a single bond,

[0056] R 0 , R 00

[0057] and R 000 each independently of one another represents H or an alkyl group having 1 to 12 C atoms, and

[0058] Y x and Y x‘ Each independently represents H, F, Cl or CN.

[0059] X' is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 0 - or single key.

[0060] The preferred spacer group Sp' is -(CH2) p1 -、-(CF2) p1 -、-(CH2CH2O) q1 -CH2CH2-, -(CF2CF2O) q1 -CF2CF2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 00 R 000 -O) p1- , wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 00 and R 000 has the meaning given above.

[0061] Particularly preferred group -X'-Sp'- is -(CH2) p1 -、-O-(CH2) p1 -、-(CF2) p1 -、-O(CF2) p1 -、-OCO-(CH2) p1 - and -OC(O)O-(CH2) p1 -, wherein p1 has the meaning indicated above.

[0062] Particularly preferred radicals Sp′ are, in each case, for example straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, perfluoroethylene, perfluoropropylene, perfluorobutylene, perfluoropentylene, perfluorohexylene, perfluoroheptylene, perfluorooctylene, perfluorononylene, perfluorodecylene, perfluoroundecylene, perfluorododecylene, perfluorooctadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0063] It is particularly preferred that the group X' is -O- or a single bond.

[0064] Halogens are F, Cl, Br and I.

[0065] Alkyl in this context is straight-chain or branched and has 1 to 15 C atoms, preferably straight-chain and, unless otherwise specified, has 1, 2, 3, 4, 5, 6 or 7 C atoms, and is therefore preferably methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl.

[0066] The branched alkyl groups may be racemic or non-racemic (optically active).

[0067] In this context, alkoxy is straight-chain or branched and contains 1 to 15 C atoms. It is preferably straight-chain and, unless otherwise specified, has 1, 2, 3, 4, 5, 6 or 7 C atoms, and is therefore preferably methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy.

[0068] In this article, alkenyl is preferably an alkenyl with 2 to 15 C atoms, which is straight or branched and contains at least one C-C double bond. It is preferably straight chain and has 2 to 7 C atoms. Therefore, it is preferably vinyl, prop-1-enyl or prop-2-enyl, but-1-enyl, but-2-enyl or but-3-enyl, penta-1-enyl, penta-2-enyl, penta-3-enyl or penta-4-enyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl, hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl or hept-6-enyl. If two C atoms of the C-C double bond are substituted, alkenyl can be in the form of E and / or Z isomers (trans / cis). Generally speaking, each E isomer is preferred. Among the alkenyl groups, prop-2-enyl, but-2-enyl and but-3-enyl as well as pent-3-enyl and pent-4-enyl are particularly preferred.

[0069] In the present context, alkynyl is an alkynyl radical having 2 to 15 C atoms, which is straight-chain or branched and contains at least one C—C triple bond. 1-Propynyl and 2-propynyl and also 1-, 2- and 3-butynyl are preferred.

[0070] In formula I, aryl groups are preferably derived, for example, from the parent structures benzene, naphthalene, tetrahydronaphthalene, 9,10-dihydrophenanthrene, fluorene, indene and dihydroindene.

[0071] In formula I, preferred heteroaryl groups are, for example, five-membered rings such as furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole and 1,3,4-thiadiazole, six-membered rings such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine and 1,2,3-triazine, or fused ring, such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, benzoxazole, naphthioxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazolothiophene, 2H-chromene (2H-1-benzopyran), 4H-chromene (4H-1-benzopyran) and coumarin (2H-chromen-2-one), or a combination of these groups.

[0072] In formula I, preferred alicyclic groups are cyclobutane, cyclopentane, cyclohexane, cyclohexene, cycloheptane, decahydronaphthalene, bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, spiro[3.3]heptane and octahydro-4,7-methylenedihydroindane.

[0073] In formula I, preferred heteroaliphatic groups are tetrahydrofuran, dioxolane, tetrahydrothiophene, pyran, dioxane, dithiane, silinane, piperidine and pyrrolidine.

[0074] Preferably, A 1 and A 3 Selected identically or differently at each occurrence from the following group:

[0075] a) 1,4-phenylene, in which one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by Y,

[0076] b) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein one or more non-adjacent CH2 groups may be replaced by -O- and / or -S- and wherein, in addition, one or more H atoms may be replaced by Y, and

[0077] c) the group consisting of 1,3-dioxolane-2,4-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, 1,4-bicyclo[2.2.2]octane-1,5-diyl, piperidine-1,5-diyl and thiophene-2,5-diyl, wherein one or more H atoms may be replaced by Y,

[0078] wherein Y has the meaning given above.

[0079] In formula I and its subformulae, very preferably, A 1 and A 3 Same or different

[0080]

[0081] A 2 -Z L express

[0082]

[0083] B 1 express

[0084]

[0085] R 1 represents H, a straight-chain or branched alkyl, alkenyl, alkynyl, alkoxy radical, adamantyl or adamantylmethoxy radical each having up to 12 C atoms,

[0086] L 1 and L 2 identically or differently represent F or Cl,

[0087] Y 1 and Y 2 has, identically or differently, one of the meanings given above for Y, preferably denotes H, F or Cl,

[0088] Y 3 and Y 4 The same or different have the above Y 3 and Y 4 one of the meanings given, preferably methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, methoxy, trifluoromethyl, trifluoromethoxy or trifluoromethylthio

[0089] Z L It means -O-,

[0090] Z 1 , Z 2independently of one another represent a single bond, -C(O)O-, -OC(O)-, -CF2O-, -OCF2-, -CH2O-, OCH2- or -CH2CH2-, in particular a single bond, and / or

[0091] G represents -OP(O)(OH)2, -PO(OH)2 or -COH(PO(OH)2)2.

[0092] Very preferred subformulae of formula I are subformulae I-1 to I-6:

[0093]

[0094]

[0095] The radicals occurring therein have the meanings defined above for formula I, preferably

[0096] R 1 represents an alkyl group having 1 to 7 C atoms,

[0097] L 1 and L 2 identically or differently represent F or Cl,

[0098] Y 3 and Y 4 has, identically or differently, one of the meanings given above, preferably denotes methyl, and

[0099] G represents -PO(OH)2 or -COH(PO(OH)2)2.

[0100] According to another aspect of the present invention, there is provided a chiral non-racemic compound of formula I.

[0101] The molecular layer obtained from the chiral compound of formula I enables memristive devices with significantly reduced random noise and faster switching, thus reducing the read and write error rates, which has a positive effect on energy efficiency. In addition, an increased tunneling current is observed, which allows integration into smaller interface dimensions.

[0102] Preferably, the chiral compound has an enantiomeric excess (ee) of 50% or more, preferably 80%, 90%, 95% or more, more preferably 97% or more, especially 98% or more.

[0103] Chirality is achieved by having one or more, preferably one or two, very preferably one asymmetrically substituted carbon atoms (or: asymmetric carbon atoms, C*) in the chiral group R of the above formula I. 1 (hereinafter referred to as R*) implementation.

[0104] In R*, the asymmetric carbon atom is preferably connected to two differently substituted carbon atoms, a hydrogen atom and a substituent selected from halogen (preferably F, Cl or Br), alkyl or alkoxy having in each case 1 to 5 carbon atoms, and CN.

[0105] The chiral organic group preferably has the formula

[0106]

[0107] in

[0108] X′ has the meaning defined above for formula I, preferably represents —CO—O—, —O—CO—, —O—CO—O—, —CO—, —O—, —S—, —CH═CH—, —CH═CH—COO— or a single bond, more preferably —CO—O—, —O—CO—, —O— or a single bond, very preferably —O— or a single bond,

[0109] Q represents a single bond or an optionally fluorinated alkylene group having 1 to 10 carbon atoms, wherein the CH2 group not connected to X' can also be replaced by -O-, -CO-, -O-CO-, -CO-O- or -CH=CH-, preferably an alkylene group having 1 to 5 carbon atoms or a single bond, particularly preferably -CH2-, -CH2CH2- or a single bond,

[0110] Y represents an optionally fluorinated alkyl radical having 1 to 15 carbon atoms, in which one or two non-adjacent CH2 groups may also be replaced by -O-, -CO-, -O-CO-, -CO-O- and / or -CH=CH-; further represents CN or halogen, preferably an optionally fluorinated alkyl radical or alkoxy radical having 1 to 7 C atoms, -CN or Cl, particularly preferably -CH3, -C2H5, -CF3 or Cl,

[0111] R Ch represents an alkyl group having 1 to 15 carbon atoms, different from Y, in which one or two non-adjacent CH2 groups may also be replaced by -O-, -CO-, -O-CO-, -CO-O- and / or -CH=CH-, preferably a straight-chain alkyl group having 1 to 10, in particular 1 to 7, carbon atoms, in which the CH2 group connected to an asymmetric carbon atom may be replaced by -O-, -O-CO- or -CO-O-.

[0112] In which R 1 represents a group Dia-Z as defined above D In an embodiment, the group R* has the formula Dia-Sp*, wherein Sp* represents a chiral non-racemic spacer group.

[0113] The group Dia-Sp* preferably has the formula

[0114]

[0115] wherein Dia, Q, Y and X' have the meanings defined above, and

[0116] Q' has the same or different meaning as given to Q above.

[0117] The compounds of the general formula I are prepared by methods known per se, as described in the literature (e.g. in authoritative works, such as Houben-Weyl, Methoden der organischen Chemie [Organic Chemistry Methods], Georg-Thieme-Verlag, Stuttgart), under reaction conditions that are known and suitable for the reaction. Variants known per se can be used in this context, but are not described in more detail here. The chiral groups R* and Sp* are described in A. Taugerbeck, Ch. Booth, Design and Synthesis of Chiral Nematic Liquid Crystals, in: Handbook of Liquid Crystals, Volume 3, Part III, Chapter 14, Wiley VCH, Weinheim, 2014 and can preferably be synthesized according to the synthesis methods described herein or in the references cited herein.

[0118] If desired, the starting materials can also be formed in situ by not isolating them from the reaction mixture, but rather immediately converting them further into the compounds of the formula I.

[0119] Preferred synthetic routes for compounds of the invention are shown in the following schemes and further illustrated by working examples. The synthesis can be tailored to a particular desired compound of Formula I by selecting appropriate starting materials. For example, as shown in Scheme 1, the reaction of a phenolic or thiophenolic compound (1) with a fluoronitroaromatic compound (2) produces an aryl ether 3 by nucleophilic substitution with a fluoride. Ether 3 can be converted to phosphonic acid 5 via iodide 4 using standard methods.

[0120] Solution 1

[0121]

[0122] X=O or S.

[0123] The present invention further relates to a method for producing a switching element according to the present invention, comprising at least the following steps:

[0124] a) preparing a first electrode having a surface,

[0125] b) depositing a monolayer comprising one or more compounds of formula I on the surface of the first electrode,

[0126] c) Applying a second electrode.

[0127] The deposition of the monolayer is carried out using pure substances or from solution, preferably from solution. Suitable deposition methods and solvents are known to the person skilled in the art; examples are spin coating or dip coating.

[0128] According to another aspect of the invention, a monolayer is made from one or more compounds of formula I, wherein the anchoring group G in the compound of formula I represents -SO2OR V 、-OP(O)(OR V )2.-PO(OR V )2、-C(OH)(PO(OR V )2)2, -COOR V Or -Si(OR V )3, where R V Denotes an alkyl group having 1 to 20 C atoms, preferably a secondary or tertiary alkyl group having up to 20 C atoms. These compounds are notable for a particularly high solubility and are particularly suitable for industrial processes, such as spin coating. In addition, these compounds can be processed by vapor deposition. The compounds are used as precursors for the corresponding free acids, wherein the free acids are obtained in situ by heat treatment of the compounds after deposition on the first electrode. The first electrode is then heated to a temperature of 60° C. to 300° C., preferably 100° C. to 250° C., in particular 140° C. to 180° C.

[0129] In a preferred embodiment, after the deposition of the monolayer, the substrate is annealed. The annealing is carried out at a temperature of more than 20° C. and less than 300° C., preferably more than 50° C. and less than 200° C., particularly preferably more than 90° C. and less than 150° C. The duration of the annealing is 1 to 48 h, preferably 4 to 24 h, particularly preferably 8 to 16 h.

[0130] The molecular layer of the present invention is a layer of electrically insulating, non-conductive and non-semi-conductive organic compounds.

[0131] The molecular layer preferably comprises molecules of the formula I or particularly preferably consists of molecules of the formula I.

[0132] The thickness of the layer is preferably 10 nm or less, particularly preferably 5 nm or less, very particularly preferably 2 nm or less.

[0133] The molecular layer may consist of one, two, three or more molecular layers comprising the compound of formula I.

[0134] The molecular layer used according to the invention is preferably a molecular monolayer.

[0135] In one embodiment, the molecular layer is a self-assembled monolayer (SAM).

[0136] The preparation of self-assembled monolayers is known to the person skilled in the art; an overview is given, for example, in A. Ulman, Chem. Rev. 1996, 96, 1533-1554.

[0137] In another embodiment, the molecular layer is bonded to the substrate by chemical adsorption, in particular an addition reaction or a condensation reaction.

[0138] In another embodiment, the molecular layer is bound to the substrate by physical adsorption.

[0139] The coverage of the substrate is preferably from 90% to 100%, particularly preferably from 95% to 100%, very particularly preferably from 98% to 100%.

[0140] In another embodiment, the molecular layer is covered with 1 to 10, preferably 1 to 5, particularly preferably 1 to 3 further layers of organic or inorganic adsorbates. Suitable layers include, for example, dielectrics, such as oxidized, fluorinated or nitrided materials, such as TiO2, Al2O3, HfO2, SiO2, LiF and Si3N4; or metals, such as Pt, Pd, Pb, Au, Ag, Cu, Al and Mg, and eutectic compounds thereof, such as PdAu 20:80. The layers can be built up with a thickness of a few nanometers by defined and high-precision deposition, for example by ALD (atomic layer deposition) processes.

[0141] The molecules of the molecular layer are preferably covalently bonded to the substrate. The bonding is carried out by known methods familiar to the person skilled in the art, for example by addition reaction of compounds of the formula I or by esterification using hydroxyl groups located on the surface of the substrate.

[0142] For the addition reaction, suitable substrates, preferably silicon surfaces, can be treated, for example, to obtain hydrogen-terminated surfaces after corresponding pretreatment with aqueous NH4F solution. The surface treated in this way can then be treated directly with a suitable liquid compound of formula I or a solution of a compound of formula I in a suitable solvent at elevated temperature with the exclusion of oxygen. According to this aspect of the invention, the group G in formula I preferably represents -CH=CH2.

[0143] For the condensation reaction, suitable substrates, preferably silicon surfaces, can be treated, for example, with oxygen plasma to obtain a hydrophilic oxidized surface full of hydroxyl groups. The surface treated in this way can then be directly reacted with a suitable liquid compound of formula I or a solution of a compound of formula I in a suitable solvent at elevated temperatures. Obviously, this type of oxidized surface is only used for surface modification, the purpose of which is to be derived via a condensation reaction, and does not represent an insulating layer in the true sense. Due to the low thickness of about 1 nm, the tunneling current through this oxidized surface can be large enough.

[0144] In the switching element of the present invention, the molecules of the molecular layer are bound to a substrate or an intermediate layer between the molecular monolayer and the substrate. Depending on the structure of the switching element, the substrate of the present invention can perform various functions. For example, a conductive substrate can be used as a first electrode. Similarly, the substrate can be a layer of a diode.

[0145] Suitable substrates are known to those skilled in the art. Particularly suitable substrates are selected from:

[0146] - single-element semiconductors, such as Si, Ge, C (diamond, graphite, graphene, fullerene), α-Sn, B, Se and Te;

[0147] - Compound semiconductors, preferably

[0148] -III-V semiconductors, especially GaAs, GaP, InP, InSb, InAs, GaSb, GaN, TaN, TiN, MoN, WN, AlN, InN, Al x Ga 1-x As and In x Ga 1-x Ni,

[0149] -II-VI semiconductors, especially ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, Hg (1-x) Cd (x) Te, BeSe, BeTe x and HgS;

[0150] -III-VI semiconductors, especially GaS, GaSe, GaTe, InS, InSe x and InTe,

[0151] - Group I-III-VI semiconductors, in particular CuInSe2, CuInGaSe2, CuInS2 and CuInGaS2,

[0152] - Group IV-IV semiconductors, especially SiC and SiGe,

[0153] - Group IV-VI semiconductors, especially SeTe;

[0154] - organic semiconductors, in particular polythiophenes, tetracene, pentacene, phthalocyanine, PTCDA, MePTCDI, quinacridone, acridone, indanthrone, flavanthrone, perinone, AlQ3 and mixed systems, in particular PEDOT:PSS and polyvinylcarbazole / TLNQ complexes;

[0155] - metals, in particular Ta, Ti, Co, Mo, Pt, Ru, Au, Ag, Cu, Al, W and Mg;

[0156] - Conductive oxide materials, in particular indium tin oxide (ITO), indium gallium oxide (IGO), InGa-α-ZnO (IGZO), aluminum-doped zinc oxide (AZO), tin-doped zinc oxide (TZO), fluorine-doped tin oxide (FTO) and antimony tin oxide.

[0157] The molecular layer may also optionally be bonded to a thin (preferably 0.5-5 nm thick) oxidized or fluorinated intermediate layer, such as TiO2, Al2O3, HfO2, SiO2 or LiF, located on the substrate.

[0158] The counter electrode or second electrode consists of a conductive or semiconductive material or a combination of a plurality of these materials (layer stack). Examples are the materials mentioned as substrate materials. Preferred are Hg, In, Ga, InGa, Ag, Au, Cr, Pt, PdAu, Pb, Al, Mg, W, Yb, Zn, CNT (carbon nanotubes), graphene and conductive polymers (e.g. PEDOT:PSS).

[0159] The preparation and structuring of the electrodes are carried out by methods known to those skilled in the art. The fabrication and electrical characterization of switching elements comprising a molecular layer obtained from one or more compounds of formula I are carried out according to the procedures described in WO 2016 / 110301 A1 and WO 2018 / 007337 A2. Example

[0160] Synthesis Example 1

[0161] Step 1: 1-(2,6-dimethyl-4-nitro-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)-benzene

[0162]

[0163] A solution of 2-fluoro-1,3-dimethyl-5-nitrobenzene (24.5 g, 0.145 mol) in dimethyl sulfoxide (DMSO) (245 mL) was added to a suspension of 2,3-difluoro-4-(4-pentylcyclohexyl)phenol (49.1 g, 0.174 mol) and potassium carbonate in DMSO (245 mL) and heated overnight at 125° C. under nitrogen. The mixture was cooled to 40° C. and then added to water (1.5 L) and stirred for 30 min. Ethyl acetate (400 mL) and brine (50 mL) were added and the layers were separated. The aqueous layer was further extracted with ethyl acetate (2×300 mL). The organics were combined, dried over magnesium sulfate and the solvent evaporated. The crude oil was dissolved in heptane (160 mL) and purified on silica gel (200 g) eluting with heptane followed by 5% ethyl acetate / heptane followed by recrystallization from acetonitrile to afford 1-(2,6-dimethyl-4-nitro-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)-benzene as a beige solid.

[0164] 1 H NMR(400MHz, CDCl3-d)δppm 0.89(3H,t,J=7.0Hz),1.00-1.15(2H,m),1.17-1.35(9H,m),1.35-1.46(2H,dd,J=12.3Hz,2.3H z),1.86(4H,br.d,J=10.9Hz),2.25(6H,s),2.77(1H,m),6.12(1H,m),6.75(1H,m),8.02(2H,s).

[0165] 13 C NMR(400MHz, CDCl3-d)δppm 14.01,16.36,22.64,32.12,32.82,33.30,37.00,37.15,37.21,109.16(d,J=2.9Hz),120.77(t,J=5.1Hz),124.34,130.12(dd,J=12. 5Hz, 1.5Hz), 132.95, 140.69 (dd, J = 248.7Hz, 16.1Hz), 143.43 (dd, J = 8.8Hz, 2.9Hz), 144.79, 148.37 (dd, J = 247.2Hz, 10.3Hz), 155.90.

[0166] 19 F NMR (400MHz, CDCl3-d) δppm -158.9 (1F, d, J = 19.1Hz), -141.4 (1F, d, J = 19.1Hz).

[0167] Step 2: 4-[2,3-Difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-aniline

[0168]

[0169] Pd / C (5% loading, 50% wetting, 1.95 g) is loaded into a 2L Parr pressure vessel, followed by the addition of a solution of 1-(2,6-dimethyl-4-nitro-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)-benzene (39.0 g, 90.38 mmol) in isopropanol (585 mL) and tetrahydrofuran (THF, 117 mL). Hydrogen is loaded to a pressure of 5 bar. After 90 min, the pressure drops to about 1 bar. Hydrogen is loaded to a pressure of 5 bar again and stirred overnight. The catalyst is filtered off and washed with isopropanol (50 mL), and the filtrate is concentrated to dryness to obtain 4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-aniline as an off-white solid.

[0170] 1 H NMR(400MHz,DMSO-d6)δppm 0.85(3H,t,J=6.9Hz),0.95-1.07(2H,m),1.13-1.32(9H,m),1.33-1.46(2H,m),1.76(4H,t,J=14.3Hz), 1.90(6H,s),2.67(1H,tm,J=12.0Hz),3.34(1H,s),4.93(2H,s),6.20(1H,m),6.32(2H,s),6.90(1H,m).

[0171] 13 C NMR(400MHz,DMSO-d6)δppm 13.81,15.70,22.14,26.04,31.64,32.36,32.88,36.40,36.56,36.78,109.27,114.03,121.12(m),127.46(d,J =11.7Hz), 130.19, 139.63 (dd, J = 245.4Hz, 15.8Hz), 140.27, 145.1 (m), 146.13, 148.65 (dd, J = 243.6Hz, 10.3Hz).

[0172] 19 F NMR (400MHz, DMSO-d6) δppm -160.90 (1F, d, J = 21Hz), -143.67 (1F, d, J = 21Hz).

[0173] Step 3: 2,3-Difluoro-1-(4-iodo-2,6-dimethyl-phenoxy)-4-(4-pentylcyclohexyl)benzene

[0174]

[0175] To a solution of 4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-aniline (29.8 g, 74.22 mmol) in dichloromethane (218 mL) was added a solution of sodium nitrite (25.6 g, 371.1 mmol) in water (218 mL), followed by diiodomethane (39.76 g, 148.4 mmol). The mixture was stirred for 15 min, and then acetic acid (89.1 g, 1.48 mol) was added dropwise. The mixture was stirred at room temperature overnight. The layers were separated and the aqueous layer was extracted with dichloromethane. The organics were combined and washed with 20% sodium bisulfite and brine. The organics were dried over magnesium sulfate and concentrated to dryness to obtain a crude material as a red oil. The oil was purified on silica gel eluting with 2.5% dichloromethane / heptane and recrystallized from hot acetonitrile to afford 2,3-difluoro-1-(4-iodo-2,6-dimethyl-phenoxy)-4-(4-pentylcyclohexyl)benzene as a white solid.

[0176] 1 H NMR(400MHz, CDCl3-d)δppm 0.91(3H,t,J=7.0Hz),1.04-1.12(2H,m),1.18-1.47(11H,m),1.87(4H,br.d,J=10. 8Hz), 2.12(6H,s), 2.77(1H,tm,J=12.2Hz), 6.14(1H,m), 6.72(1H,m), 7.46(2H,m).

[0177] 13 C NMR(400MHz, CDCl3-d)δppm 14.11,15.77,22.69,26.60,32.17,32.89,33.37,36.98,37.20,37.27,89.70,108.98(d,J=3.7Hz),120.55(m),129.24(d,J=12 .5Hz), 133.81, 137.84, 140.64 (dd, J = 248.0Hz, 16.2Hz), 144.13 (dd, J = 8.1Hz, 2.9Hz), 149.54 (dd, J = 246.5Hz, 10.3Hz), 150.79.

[0178] 19F NMR (400MHz, CDCl3-d) δppm -159.79 (1F, d, J = 20.5Hz), -142.22 (1F, d, J = 20.5Hz).

[0179] Step 4: 1-(4-diethoxyphosphoryl-2,6-dimethyl-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)benzene

[0180]

[0181] To a solution of 2,3-difluoro-1-(4-iodo-2,6-dimethyl-phenoxy)-4-(4-pentylcyclohexyl)benzene (28.5 g, 55.62 mmol) in dioxane (285 mL) under nitrogen was added triethyl phosphite (23.1 g, 139.05 mmol). Pd(OAc)2 (1.56 g, 6.95 mmol) was added and the reaction was heated to reflux for 75 min. The reaction was cooled to 30 °C, heptane (400 mL) and water (400 mL) were added, the layers were separated, and the aqueous layer was extracted with ethyl acetate (400 mL). The organics were combined, washed with brine, dried over magnesium sulfate, filtered, and then concentrated to dryness. The crude material was purified on silica eluting with 10% ethyl acetate / dichloromethane to afford 1-(4-diethoxyphosphoryl-2,6-dimethyl-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)benzene as an off-white solid.

[0182] 1 H NMR(400MHz, CDCl3-d)δppm 0.89(3H,t,J=7.0Hz),1.02-1.10(2H,m),1.15-1.45(18H,m),1.84(4H,d,J=11.0Hz),2.18 (6H,s),2.75(1H,m),4.06-4.23(4H,m),6.09(1H,m),6.71(1H,m),7.56(2H,d,J=13.3Hz).

[0183] 13C NMR(400MHz, CDCl3-d)δppm 13.97,16.03,16.25(d,J=6.6Hz),22.58,26.49,32.06,32.79,32.26,36.88,37.09,37.16 ,62.07(d,J=5.9Hz),109.08(d,J=2.9Hz),120.51(t,J=5.1Hz),125.15(d,J=189.3Hz),12 9.36(d,J=11.7Hz),131.82(d,J=16.1Hz),132.64(d,J=10.3Hz),140.58(dd,J=248.3Hz,1 5.8Hz), 143.82 (dd, J = 8.4Hz, 2.6Hz), 149.47 (dd, J = 246.2Hz, 9.9Hz), 154.16 (d, J = 3.7Hz).

[0184] 19 F NMR (400MHz, CDCl3-d) δppm -159.6 (1F, d, J = 19Hz), -142.1 (1F, d, J = 19Hz).

[0185] 31 P NMR (400MHz, CDCl3-d) δppm 18.80.

[0186] Step 5: [4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-phenyl]phosphonic acid

[0187]

[0188] To 1-(4-diethoxyphosphoryl-2,6-dimethyl-phenoxy)-2,3-difluoro-4-(4-pentylcyclohexyl)benzene (22.35 g, 42.77 mmol) in dichloromethane (325 mL) was added trimethylsilyl bromide (65.82 g, 427.7 mmol) dropwise. The solution was stirred overnight at room temperature. Methanol (225 mL) was added over 15 min and the solution was stirred for 30 min and then concentrated to dryness. The resulting solid was dissolved in tetrahydrofuran (325 mL) and filtered through a 0.7μ glass fiber filter. Heptane (225 mL) was added and THF was slowly removed until solids began to precipitate, at which time, evaporation was stopped and the mixture was allowed to cool to room temperature while stirring overnight. The resulting solid was filtered off, washed with heptane and recrystallized from ethyl acetate to obtain [4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-phenyl]phosphonic acid as a white solid.

[0189] 1H NMR(400MHz,THF-d)δppm 0.90(3H,t,J=7.0Hz),1.03-1.14(2H,m),1.21-1.35(9H,m),1.42-1.52(2H,m),1.85(4H,t,J=1 3.0Hz), 2.14(6H,s), 2.77(1H,tm,J=12.1Hz), 6.20(1H,m), 6.80(1H,m), 7.59(2H,d,J=13.4Hz).

[0190] 19 F NMR (400MHz, THF-d) δppm -162.86 (1F, d, J = 20.4Hz), -145.71 (1F, d, J = 20.4Hz).

[0191] 31 P NMR (400MHz, THF-d) δppm 15.91.

[0192] ES(-ve)MS:m / z=465.1998,100%[MH] - ,C 25 H 32 F2O4P - Requirement 465.2006.

[0193] Analogously to Example 1, the following compound was obtained:

[0194] Compound No.

[0195]

[0196]

[0197]

[0198]

[0199]

[0200]

[0201]

[0202]

[0203]

[0204] Comparative Solubility Testing

[0205] The following reference compound 1 was determined experimentally (see DE102017005884):

[0206]

[0207] Comparative solubility of Synthesis Example 1 in various solvents at 1 mM concentration at 23°C. The samples were stirred at 23°C for 18 h and then visually inspected. In the following table, the expression "soluble" means that a clear solution was obtained after 18 h. "Insoluble" means that residual solids were observed.

[0208]

[0209]

[0210] In contrast to Reference 1, Synthesis Example 1 was dissolved in industrially typical, environmentally acceptable CMOS processing solvents 1-methoxy-2-propanol acetate and cyclohexanone at a concentration of 1 mM.

[0211] Electrical characterization

[0212] The switching device 100 ( Figure 1 ) was electrically characterized using a nanoprobe (Hitachi High Technologies Nano-Probe N-6000SS, probe size of about 1 μm) and an Agilent B1500 device analyzer under SEM control. The molecular layer was obtained from the compound [4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-phenyl]phosphonic acid (Synthesis Example 1) and sandwiched between a TiN first electrode 130 (thickness 50 nm) on a silicon substrate 110 with a silicon oxide layer 120 and a Ti second electrode 150 (10 nm) with a gold contact 160 (80 nm).

[0213] For comparison, a switching device including a molecular layer prepared from 11-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]undecylphosphonic acid (PA-110-YC-5, Reference Compound 1) was fabricated and characterized accordingly.

[0214] The starting material was a 6 inch diameter silicon-on-insulator wafer (“SOI wafer”) having a 110 nm thick silicon layer with a

[100] orientation and a resistivity of about 20 Ω.cm on a 200 nm thick silicon oxide layer on a lightly boron-doped silicon wafer with a thickness of 525 μm and a

[100] orientation.

[0215] The upper silicon layer is highly boron doped by ion implantation (doping concentration c ~ 5×10 19 cm -3, resistivity ρ ~ 1.4 mΩ.cm). After doping, the wafer was divided into square sections ("chips") measuring 8 mm x 8 mm. In each case, the chips were first cleaned in acetone and then in isopropanol in an ultrasonic bath for 10 min. The silicon dioxide intermediate layer 120 was produced by treating the wafer with oxygen plasma (200 W, 7 min).

[0216] The substrate is then coated with a 50 nm thick TiN layer by reactive sputtering deposition, activated by ozone / UV treatment (110 W / 300 s), and then immersed in a 1 mM solution of phosphonic acid [4-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]-3,5-dimethyl-phenyl]phosphonic acid (Synthesis Example 1) in tetrahydrofuran (THF) for 24 h. The chip is removed from the immersion bath, blown dry with nitrogen and annealed at nitrogen and 120° C. for 60 min. The chip is then rinsed with THF on a spin coater and then annealed again at nitrogen and 120° C. for 5 min. Titanium top electrodes 150 and gold contacts 160 are applied by sputtering using standard processes.

[0217] The electrical characterization results of the device 100 are shown in Figure 2 The forward scan 210 starts at 0 V and the voltage increases to +3.5 V; the reverse scan 220 then returns to 0 V, further to -3.5 V, and then returns to 0 V. The scan rate is 300 mV / s. The resulting current is measured and the results are shown in Figure 2 The device has an advantageously large memory window.

[0218] Figure 3 Shown is the current density of a device made with a comparative compound, Reference Compound 1. The comparison shows that devices made with the compounds of the present invention exhibit advantageously high current densities, about 1000 times higher.

Claims

1. A compound of formula I R 1 -(A 1 -Z 1 ) r -B 1 -Z L -A 2 -(Z 3 -A 3 ) s -G(I) in R 1 represents a straight-chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, wherein one or more CH2 radicals in these radicals can each independently be replaced by -C≡C-, -CH=CH-, -O-, -S-, -CF2O-, -OCF2-, -CO-O-, -O-CO-, -SiR 0 R 00 -、-NH-、-NR 0 - or -SO2- is substituted in such a way that the O atoms are not directly connected to each other, and wherein, Furthermore, one or more H atoms may be replaced by halogen, CN, SCN or SF5, or R 1 Represents the group Dia-Z D , Dia represents an adamantane group, Z D With Z 1 and Z 3 or a linear or branched spacer group, Z 1 , Z 3 represents, identically or differently on each occurrence, a single bond, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CH2O-, -OCH2-, -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -(CH2) n1 -、-(CF2) n2 -, -CF2-CH2-, -CH2-CF2-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH2) n3 O-, -O(CH2) n4 -, -C≡C-, -O-, -S-, -CH=N-, -N=CH-, -N=N-, -N=N(O)-, -N(O)=N- or -N=CC=N-, n1, n2, n3, n4 are identical or different and are 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, R 0 , R 00 represent, identically or differently, alkyl or alkoxy radicals having 1 to 15 C atoms, in which one or more H atoms may be replaced by halogen, A 1 , A 3 represents, identically or differently on each occurrence, an aromatic, heteroaromatic, cycloaliphatic or heteroaliphatic ring having 4 to 25 ring atoms, which may also contain fused rings and which may be mono- or polysubstituted by Y, A 2 -Z L express in Y 3 and Y 4 has the same or different meaning as given to Y, and Z L Indicates -O-, -S-, -CH2-, -C(O)-, -CF2-, -CHF-, -C(R x )2-, -S(O)- or -SO2-, Y, identically or differently on each occurrence, represents F, Cl, CN, SCN, SF5, or linear or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, or cycloalkyl or alkylcycloalkyl having 3 to 12 C atoms, B 1 express These groups can be oriented in two directions, L 1 To L 5 independently represent F, Cl, Br, I, CN, SF5, CF3 or OCF3, wherein L 3 Alternatively, H can be represented as G represents -CH=CH2, -OH, -CH(CH2OH)2, -C(CH2OH)3, -B(OH)2, -SH, -SO2OH, -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2, -COOH, -Si(OR x )3, -SiCl3, -SO2OR V , -OP(O)(OR V )2, -PO(OR V )2, -C(OH)(PO(OR V )2)2, -COOR V or -Si(OR V )3, R V represents an alkyl group having 1 to 20 C atoms, R x represents a straight-chain or branched alkyl group having 1 to 6 C atoms, and r is 0, 1, or 2, s is 0, 1, or 2, Where r+s≤4.

2. Compounds according to claim 1, in which Y, identically or differently on each occurrence, represents methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, trifluoromethyl, methoxy or trifluoromethoxy.

3. The compound according to claim 1, wherein L 1 To L 5 represents Cl or F independently of each other, wherein L 3 H may also be represented alternatively.

4. The compound according to claim 1, wherein R V represents a secondary or tertiary alkyl radical having 3 to 10 C atoms.

5. A compound according to claim 1, wherein group B 1 express 6. A compound according to any one of claims 1 to 5, wherein A 1 and A 3 Selected identically or differently at each occurrence from the following group: a) 1,4-phenylene, in which one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by Y, b) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein one or more non-adjacent CH2 groups may be replaced by -O- and / or -S- and wherein, Furthermore, one or more H atoms may be replaced by Y, and c) the group consisting of 1,3-dioxolane-2,4-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, 1,4-bicyclo[2.2.2]octane-1,5-diyl, piperidine-1,5-diyl and thiophene-2,5-diyl, wherein one or more H atoms may be replaced by Y, wherein Y has the meaning given in claim 1.

7. A compound according to any one of claims 1 to 5, wherein R 1 denotes H, straight-chain or branched alkyl, alkenyl, alkynyl or alkoxy radicals each having up to 12 C atoms, or adamantyl or adamantylmethoxy radicals.

8. A compound according to claim 6, wherein R 1 denotes H, straight-chain or branched alkyl, alkenyl, alkynyl or alkoxy radicals each having up to 12 C atoms, or adamantyl or adamantylmethoxy radicals.

9. A compound according to any one of claims 1 to 5, wherein Z L Means -O-.

10. The compound according to claim 6, wherein Z L Means -O-.

11. The compound according to claim 7, wherein Z L Means -O-.

12. A compound according to any one of claims 1 to 5, wherein G represents -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2.

13. A compound according to claim 6, wherein G represents -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2.

14. A compound according to claim 7, wherein G represents -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2.

15. A compound according to claim 9, wherein G represents -OP(O)(OH)2, -PO(OH)2, -C(OH)(PO(OH)2)2.

16. The compound according to any one of claims 1 to 5, wherein s is 0.

17. The compound according to claim 6, wherein s is 0.

18. The compound according to claim 7, wherein s is 0.

19. The compound according to claim 9, wherein s is 0.

20. The compound according to claim 12, wherein s is 0.

21. A compound according to any one of claims 1 to 5, wherein Z 1 Represents a single bond.

22. The compound according to claim 6, wherein Z 1 Represents a single bond.

23. A compound according to claim 7, wherein Z 1 Represents a single bond.

24. A compound according to claim 9, wherein Z 1 Represents a single bond.

25. The compound according to claim 12, wherein Z 1 Represents a single bond.

26. The compound according to claim 16, wherein Z 1 Represents a single bond.

27. A method for preparing a switching element, comprising at least the following steps: a) preparing a first electrode having a surface, b) depositing on the surface of the first electrode a molecular layer comprising one or more compounds of the formula I according to any one of claims 1 to 26, c) Applying a second electrode.

28. A method according to claim 27, wherein the first electrode comprises a material selected from the following: a single semiconductor Si; Ge; C selected from diamond, graphite, graphene; Sn with α modification, and Se; compound semiconductors GaAs, InAs, InP, GaSb, TaN, TiN, MoN, WN and GaN, CdSe and ZnS; metals Au, Ag, Cu, Al, W, Ta, Ti, Co, Mo, Pt, Ru and Mg; and conductive oxide materials ITO, IGO, IGZO, AZO and FTO.

29. A switching element obtainable by a method according to claim 27 or 28, comprising a molecular layer sandwiched between a first electrode and a second electrode.

30. The switching element according to claim 29, wherein the molecular layer is a self-assembled monolayer.

31. A memristive device comprising a switching element according to claim 29 or 30.

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