Molecular organic crystal-based labeling system

Abstract

The invention relates to a labeling technique formed by using molecular organic crystals having non-reproducible random position, shape, color and orientation, as well as specific fluorescence emission and physicochemical properties.

Description

[0001] MOLECULAR ORGANIC CRYSTAL-BASED LABELING SYSTEM Technical Field of the Invention

[0002] The invention relates to a labeling technique formed by using molecular organic crystals having random position, shape, orientation, color, specific fluorescence emission and physicochemical properties.

[0003] State of the Art Regarding the Invention

[0004] With the developing technology and the increase in global trade, the importance of labeling systems against counterfeit products has increased. While these labeling systems have traditionally taken the form of watermarks, QR codes, water marks or topographic reliefs, etc., in recent years, with the development of nanotechnology and materials science, nanomaterials and functional materials have been used in labeling systems.

[0005] Many of the security tags used for anti-counterfeiting and authentication purposes are generally produced in deterministic ways, i.e. in reproducible ways. These labels traditionally use watermarks, geometric images based on barcodes or QR codes, etc. The disadvantage of labels produced in these ways is that they can be reproduced and imitated if the production stage is known. A study at the Massachusetts Institute of Technology has demonstrated a stochastic (completely random) label formation approach as an alternative to one-way mathematical functions. This newly introduced labeling system is called PUF (physically unclonable function). (Science 2002, 297, 2026-2030). Since stochastically generated labeling systems are generated completely dependent on randomness, it is impossible to reproduce them, even by the manufacturer.

[0006] Some disadvantages of physically unclonable function-based labeling methods are the limited number of raw materials that can be used and the limited encoding capacity. For example, patent document W02020117950A1 describes PUFs produced using metals with branched dentritic structures that are formed in a stochastic process. It is mentioned that by taking advantage of the fact that these branched structures are formed in different and non-reproducible ways each time, the security labels are obtained. Again, the formation of PUF structures requires a limited range of surfaces and materials that are treated with specific modifications. These dendrite structures do not have additional security layers such as structural color and fluorescence emission and unique physicochemical properties. In addition, there are difficulties in integrating the PUFs produced into a final product.

[0007] As a result, all the above-mentioned problems have made it necessary to realize a novelty in the relevant field.

[0008] Objects and Summary of the Invention

[0009] The main object of the invention is to use organic ^-conjugated molecules and relatively simple solvent-based processing methods in PUF production to form molecular microcrystals with random positions, different sizes, structural colors and shapes, specific fluorescence emission and physicochemical properties.

[0010] The invention achieves this object by forming crystals in random positions and microscopic sizes with a high variety of structural colors, orientations, shapes and sizes. The specific fluorescence emission and physicochemical properties of the organic ^-conjugated molecule offer additional security layers.

[0011] By using the unique organic molecules synthesized within the invention, PUF labels with multiple security layers can be obtained directly on surfaces with simple production steps.

[0012] By using the organic solutions that are obtained from the ^-conjugated molecules used in the invention, depending on the molecular structure and solution parameters such as concentration etc., the microcrystals in completely random positions, different shapes, orientations, thicknesses and different colors are formed on the surface.

[0013] The position of the microcrystals, as well as the randomness of their color, size and shape, increases the encoding capacity.

[0014] In addition, the unique fluorescence emission characteristics of ^-conjugated molecules and fingerprint molecular vibrations provide additional security layers. Definitions of Drawings Describing the Invention

[0015] Fig. la A representative view of the formation stages of the microcrystals of the invention.

[0016] Fig. lb A representative view of the encryption algorithm of the microcrystals of the invention.

[0017] Fig. 1c A representative view of the optical imaging and analysis.

[0018] Fig. 2a The molecular microcrystalline-based unclonable surfaces produced from fluorescent small molecule (FSM) solution of Formula 2 on silicon substrate surfaces, a) Bright field optical images of microcrystalline-based unclonable surfaces at low and high magnifications, b) dark field optical image of microcrystalline-based unclonable surfaces, c) fluorescence optical image of microcrystalline-based unclonable surfaces, d) scanning electron microscope (SEM) image of microcrystalline-based unclonable surfaces, all of which are captured from the same region.

[0019] Fig. 2b Molecular microcrystalline-based unclonable surfaces produced from FSM solution of Formula 2 on different substrate surfaces a) optical microscope image of molecular microcrystals produced on silicon substrate b) optical microscope image of molecular microcrystals produced on glass substrate c) optical microscope image of microcrystals on SiO2substrate.

[0020] Fig.3a Molecular microcrystalline-based unclonable surfaces obtained from FSM solutions of Formula 2 applied with a brush on silicon substrates, a) bright field optical images of microcrystalline-based unclonable surfaces at different magnifications b) dark field optical image of microcrystalline-based unclonable surfaces c) SEM image of microcrystalline-based unclonable surfaces.

[0021] Fig. 3b Bright field optical images of molecular microcrystalline-based unclonable surfaces produced from FSM solutions of Formula 2 on PMMA photoresist-coated substrate surfaces at different magnifications.

[0022] Fig. 3c The molecular microcrystalline-based unclonable surfaces produced from organic molecule solution of Formula 4 on silicon substrate surfaces. Bright field optical images of microcrystalline-based unclonable surfaces at different magnifications b) fluorescence optical image of microcrystalline-based unclonable surfaces at different magnifications, c) dark field optical image of microcrystalline based unclonable surfaces.

[0023] Fig. 4 A synthesis diagram of molecules of formula 2-5 and the corresponding intermediate compounds.

[0024] Detailed Description of the Invention

[0025] The subject matter of the invention is to provide a stochastically generated labeling system using ^-conjugated molecules, providing a multi-layered security system. The invention provides an advantage over previous stochastic labeling systems using ^-conjugated molecules in terms of increasing security layers and encoding capacity.

[0026] The method of the invention is the coating of organic molecule solutions prepared at appropriate parameters on a surface by spin-coating method to form a thin film and the formation of molecular crystals at random positions on the surface of an organic thin film using solvent vapor annealing or thermal annealing of the films. Thanks to this method, a stochastic process is created and the microcrystals placed completely randomly on the film to be used in labeling are generated.

[0027] The preferred technique in the invention is oligonophenylacetylene-based small molecules that also have fluorescence properties. Although the invention is described in terms of the preferred technique, it is not limited thereto. The chemical formula of oligonophenylacetylene molecules is shown below.

[0028]

[0029] Formula 1

[0030] Formula 1 describes the general formulation of functionalized oligophenylacetylene-based fluorescent synthesis molecules. The molecules that form the basis of the thin film were prepared in this context. The molecules used in FSM based PUFs that rely on functionalized oligonophenylacetylene have the above general formula (Formula 1).

[0031] Xi and X2 in Formula can independently be selected from hydrogen atom, linear or branched, saturated or unsaturated alkyl chain containing 1 to 40 carbon atoms, linear or branched, saturated or unsaturated alkoxy chain containing 1 to 40 carbon atoms, or linear or branched, saturated or unsaturated oligoethylene glycol chain containing 1 to 40 carbon atoms.

[0032] Ari and An in Formula may be independently selected as either an aryl group containing 6 to 20 carbon atoms or a heteroaryl group containing 5 to 20 ring atoms, optionally these aryl or heteroaryl groups may be substituted with cyano (-CN), nitro (-NO2), fluorine (-F) / chlorine (-Cl) / bromine (-Br) / iodine (-1) halogen atoms, trifluoromethyl (-CF3) group, linear or branched, saturated or unsaturated alkyl chain containing 1 to 40 carbon atoms, linear or branched, saturated or unsaturated alkoxy chain containing 1 to 40 carbon atoms or linear or branched, saturated or unsaturated oligoethylene glycol chain containing 1 to 40 carbon atoms.

[0033] 'a’ is 0 or 1.

[0034] An illustration of the synthesis of final molecules used for PUF applications and the intermediate compounds required for the synthesis of these molecules is shown in Fig. 4. The final molecules used in organic molecule-based PUF applications are indicated as “Formula 2”, “Formula 3”, “Formula 4” and “Formula 5”; the intermediate compounds required for the synthesis of these molecules are indicated by the numbers “1”, “2” and “3”.

[0035] In the following, the synthesis methods of these intermediate compounds are described in detail and illustrated through a synthesis scheme.

[0036] Synthesis of 1.4-dibromo-2.5-bis(2-ethylhexyloxy)benzene (Compound 1):

[0037] To a mixture of potassium carbonate (3.09 g, 22.36 mmol) and 2 -ethylhexylbromide (6.06 g, 31.38 mmol) dissolved in 35 mL DMF, 2,5-dibromohydroquinone (3.1 g, 11.56 mmol) was added slowly under nitrogen. The final reaction solution is stirred at 100°C for 48 hours. The mixture is then cooled to room temperature. The reaction mixture is washed with water and the organic phase is removed with dichloromethane, dried with Na2SC>4, filtered and evaporated to dryness to give the crude product. The crude product is then purified by flash chromatography using silica gel and hexane. Compound 1 is obtained as a colorless oil.

[0038] Synthesis of L4-bis(ethynyltrimethylsilane)-2,5-bis(2 -ethylhexyloxy )benzene (Compound 2):

[0039] Compound l,4-dibromo-2,5-bis(2 -ethylhexyloxy )benzene (Compound 1) (5 g, 10.16 mmol), Pd(PPh₃)₂Cl₂ (0.428 g, 0.61 mmol) and Cui (0.098 g, 0.508 mmol) in Et N (75 mL) is stirred for ten minutes. Ethynyltrimethylsilane (2.50 g, 25.4 mmol) is then added and the reaction mixture is heated at 90°C under nitrogen for 48 hours. The reaction mixture is then cooled to room temperature and filtered. The filtrate is evaporated to dryness to obtain the crude product. The crude product is then purified by flash chromatography using hexane: ethyl acetate (30:1) and silica gel. Compound 2 is obtained as a yellow oil.

[0040] Synthesis of L4-bis(ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (Compound 3):

[0041] A suspension (175 mL) of l,4-bis(ethynyltrimethylsilane)-2,5-bis(2-ethylhexyloxy)benzene (compound 2) (3.12 g, 5.92 mmol) and KOH (9.98 g, 117.9 mmol) in THF:methanol (9:1) is stirred at room temperature for 1 hour. The reaction mixture is washed with water and the organic phase is removed with dichloromethane, dried with Na2SO4, filtered and evaporated to dryness. Compound 3 is obtained as a yellow oil.

[0042]

[0043] The formulas and synthesis methods of the compounds of Formula 2-5 synthesized via the intermediate compounds synthesized above are described in detail below. Exemplary PUFs based on oligophenylacetylene-based small molecules substituted with cyano (-CN) and branched, saturated alkyl chains have the following formula properties:

[0044] Xi and X2 is -O(CH2)CH(C2H5)(C4H9) alkoxy group,

[0045]

[0046] 'a’ is 0.

[0047] This is the 2,2'-((2,5-bis((2-ethylhexyl)oxy)-l,4-phenylene)bis(ethyne-2,l-diyl))dibenzonitrile compound of the following formula, that is, compound of Formula 2. A synthesis of the formula can be seen in reference [1].

[0048]

[0049] Formula 2

[0050] The synthesis of Formula 2 is accomplished by the following chemical processes and methods: The reactants 2-iodobenzonitrile (1.108 g, 4.84 mmol), Cui (0.018 g, 0.096 mmol), and Pd(PPh₃)₂Cl₂ (0.136 g, 0.194 mmol) in Et3N: THF (2:1) (60 mL) are stirred for 5 min. Then, 1,4-bis(ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (Compound 3) (0.74 g, 1.94 mmol) in 10 mL of THF was added and the resulting reaction mixture was heated at 80°C under nitrogen for 24 h. Then, the solution is cooled to room temperature and evaporated to dryness. The product is purified by flash column chromatography using silica gel and hexane:ethylacetate (3:1). The pure product is obtained as a light yellow solid.

[0051]

[0052] Formula 2

[0053] 3

[0054] Exemplary PUFs based on another oligophenylacetylene-based small molecules substituted with cyano (-CN) and branched, saturated alkyl chains have the following formula properties: Xi and X2 is -O(CH2)CH(C2H5)(C4H9) alkoxy group,

[0055]

[0056] ’a’ is 0.

[0057] This is the 5,5'-((2,5-bis((2-ethylhexyl)oxy)-l,4-phenylene)bis(ethyn-2,l-diyl))bis(thiophene-2-carbonitrile) compound of the following formula, that is, compound of Formula 3.

[0058]

[0059] Formula 3

[0060] The synthesis of Formula 3 is accomplished by the following chemical processes and methods: The reactants 5-bromothiophene-2-carbonitrile (0.42 g, 2.28 mmol), Cui (0.013 g, 0.068 mmol), and Pd(PPh₃)₂Cl₂ (0.064 g, 0.092 mmol) in Et3N: THF (2:1) (30 mL) are stirred for 5 min. Then, l,4-bis(ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (Compound 3) (0.35 g, 0.91 mmol) in 5 mL of THF was added and the resulting reaction mixture was heated at 80°C under nitrogen for 24 h. Then, the solution is cooled to room temperature and evaporated to dryness. The product was purified by flash column chromatography using silica gel and hexane: ethylacetate (3:1). The pure product is obtained as a light yellow solid.

[0061]

[0062] Exemplary PUFs based on oligophenylacetylene-based small molecules substituted with trifluoromethyl (-CF3) and branched, saturated alkyl chains have the following formula properties:

[0063] Xi and X2 is -O(CH2)CH(C2H5)(C4H9) alkoxy group,

[0064]

[0065] ’a’ is 0.

[0066] This is the 6,6'-((2,5-bis((2-ethylhexyl)oxy)-l,4-phenylene)bis(ethyne-2,l-diyl))bis(3-(trifluoromethyl)pyridine) compound of the following formula, that is, compound of Formula 4.

[0067]

[0068] Formula 4

[0069] The synthesis of Formula 4 is accomplished by the following chemical processes and methods: The reactants 2-iodo-5-trifluoromethyl-pyridine (0.624 g, 2.29 mmol), Cui (0.013 g, 0.068 mmol), and Pd(PPh₃)₂Cl₂ (0.064 g, 0.092 mmol) in Et3N: THF (2:1) (30 mL) are stirred for 5 min. Then, l,4-bis(ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (Compound 3) (0.35 g, 0.91 mmol) in 5 mL of THF was added and the resulting reaction mixture was heated at 80°C under nitrogen for 24 h. Then, the solution is cooled to room temperature and evaporated to dryness. The product is purified by flash column chromatography using silica gel and hexane: ethylacetate (3:1). The pure product is obtained as a light yellow solid.

[0070]

[0071] Exemplary PUFs based on oligophenylacetylene-based small molecules substituted with two cyano (-CN) and branched, saturated alkyl chains have the following formula properties:

[0072] Xi and X2 is -O(CH2)CH(C2H5)(C4H9) alkoxy group,

[0073]

[0074] 'a’ is

[0075]

[0076] This is the 4,4'-((2,5-bis((2-ethylhexyl)oxy)-1,4-phenylene)bis(ethyne-2,1-diyl))diphthalonitrile compound of the following formula, that is, compound of Formula 5.

[0077]

[0078] Formula 5

[0079] The synthesis of Formula 5 is accomplished by the following chemical processes and methods: The reactants 4-iodophthalonitrile (0.29 g, 1.15 mmol), Cui (0.007 g, 0.034 mmol), and Pd(PPh₃)₂Cl₂ (0.032 g, 0.046 mmol) in Et3N: THF (2:1) (30 mL) are stirred for 5 min. Then, 1,4-bis(ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (Compound 3) (0.175 g, 0.45 mmol) in 5 mL of THF was added and the resulting reaction mixture was heated at 80°C under nitrogen for 24 h. Then, the solution is cooled to room temperature and evaporated to dryness. The product is purified by flash column chromatography using silica gel and hexane:ethylacetate (3:1). The pure product is obtained as a light yellow solid.

[0080]

[0081] 3 Formula 5

[0082] To generate microcrystals used for PUF applications, FSMs must first be coated onto silicon substrates by the spin-coating method. This method firstly involves pouring some solution onto the surface and then allowing the solution to flow radially towards the carrier surface, forming a thin film on the surface. Then, as a result of spin-coating, the excess solution is removed from the surface under the influence of radial forces and the thickness of the film is determined by the amount of solution deposited to the surface. The film thickness depends on parameters such as the concentration, viscosity, quantity of the solution and spin speed.

[0083] The microcrystal formation step shown in Fig. la is described below.

[0084] Two methods are proposed for the random separation of FSM molecules in the formed film.

[0085] One of them is the solvent vapor annealing method. This method is based on exposing the formed thin film to a solvent atmosphere to enhance the molecular mobility and produce micro-nano structures on the surface. A swollen and mobile thin film layer from the added solvent vapor forms nanostructures due to thermodynamic differences between the molecular blocks. In the invention process, molecular movements occur on the FSM film surface exposed to solvent vapor. In the invention related to the solvent vapor annealing method, a wide variety of solvents with different chemical structure, wetting behavior and different evaporation rate can be used for the formation of microcrystalline structures of different sizes and geometries at random locations. Therefore, many polar and apolar solvents with different vapor pressures such as ethanol, methanol, chloroform, chlorobenzene, N,N-dimethylformamide (DMF), toluene, dimethylsulfoxide (DMSO), dichloromethane (DCM), acetonitrile and tetrahydrofuran can be used as solvents in this method. Silicon substrates on which organic FSM thin films are coated with different amounts of these solvents are exposed to the vapors of the solvents in a closed environment to form molecular microcrystals. The exposure time of the thin film coated substrates to solvent vapor varies preferably from 30 minutes to 24 hours. As a result of optimizations depending on the solution parameters (organic molecule concentration, type of solvent used for solvent vapor annealing method, evaporation rate, amount of solvent, etc.) and process parameters (spin-coating speed, spin-coating time, amount of solution, ambient temperature, etc.), the size, color, characteristic shape and geometry of the microcrystals produced can be differentiated.

[0086] Another proposed method is the thermal annealing method. This method is based on the spontaneous formation of molecular microcrystals to form PUF structures by heating OFM films coated by spin-coating on substrates modified with polymer chains such as low surface energy polystyrene at specific temperatures. In this process, molecular microcrystals are formed by heating FSM thin films of preferably 2% to 4% by weight, preferably prepared with solvents such as chloroform, and formed by spin-coating at a much higher concentration than the solvent vapor annealing method for a certain period of time on hot plates heated in the temperature range of 90 to 100°C below the melting point of FSMs.

[0087] In the algorithm shown in Fig. lb, the formation of islets consisting of organic molecules thanks to the dewetting behavior that will occur with the effect of the appropriate annealing parameters selected for PUF applications, and the formation of security keys by analyzing the images taken after the formation stages of unclonable surfaces consisting of molecular microcrystals by selfcrystallization of these islets are described. Depending on the thickness of the microcrystals exhibiting the desired characteristics, different structural colors are detected in optical microscope images. The thicknesses, surface height profiles and polygon geometries of microcrystals exhibiting different structural colors are measured by atomic force microscopy (AFM) topography images to confirm the thickness-dependent color relationship. The emission images of the microcrystals are visualized by dark field microscopy and fluorescence microscopy. The optics and images captured at different magnifications and with different imaging methods are analyzed with various image and decoding algorithms, and the unique, unclonable random structure of each PUF structure is converted into binary keys consisting of 0 and 1, and these keys are converted into the binary barcodes of 64 or 256 bits. Fig. 2a shows microcrystals produced on silicon substrate surfaces and acting as PUF. Part a of the figure shows the bright field optical image, part b shows the dark field optical image, part c shows the fluorescence optical image and part d shows the electron microscopy image. Each of these optical images can be used to create a different security layer.

[0088] Fig. 2b shows the optical microscope image of the microcrystals produced on silicon substrate, glass substrate and SiO2substrate and obtained by vapor annealing method and acting as PUF, respectively.

[0089] Fig. 3a shows the bright field optical images, dark field optical images and electron microscopy images of the molecular microcrystals obtained from FSM solutions on silicon substrates, respectively.

[0090] Fig. 3b shows the bright field optical images of molecular microcrystals produced on photoresist-coated substrate surfaces and obtained from molecules of Formula 4 by solvent vapor annealing method and acting as PUF.

[0091] Fig. 3c shows the bright field optical images, fluorescence optical image, dark field optical image and electron microscope image of molecular microcrystals obtained from FSM solutions of Formula 4 on silicon substrates, respectively.

[0092] REFERENCES

[0093] [1] Highly Efficient Deep-Blue Electroluminescence Based on a Solution-Processable A-π-D-π-A Oligo(p-phenyleneethynylene) Small Molecule

Claims

CLAIMS1. A method for producing a stochastic molecular crystal that serves as a physically unclonable function, characterized in that a film is formed by spin-coating technique, the film is spread and its thickness is adjusted as a result of spin-coating, and the crystallized ^-conjugated organic molecules formed by solvent vapor or thermal annealing methods are placed in random positions, resulting in an inimitable crystalline structure.

2. A method according to claim 1, characterized in that said ^-conjugated organic molecules are Oligonophenylacetylene-based molecules substituted in various ways.

3. A method according to claim 1, characterized in that said ^-conjugated organic molecules areFormula 1wherein- Xi and X2 are independently selected from hydrogen atom, linear or branched, saturated or unsaturated alkyl chain containing 1 to 40 carbon atoms, linear or branched, saturated or unsaturated alkoxy chain containing 1 to 40 carbon atoms, or linear or branched, saturated or unsaturated oligoethylene glycol chain containing 1 to 40 carbon atoms, - Ari and An may be independently selected as either an aryl group containing 6 to 20 carbon atoms or a heteroaryl group containing 5 to 20 ring atoms, optionally these aryl or heteroaryl groups are selected from the structures substituted with cyano (-CN), nitro (-NO2), fluorine (-F) / chlorine (-Cl) / bromine (-Br) / iodine (-1) halogen atoms, trifluoromethyl (-CF3) group, linear or branched, saturated or unsaturated alkyl chain containing 1 to 40 carbon atoms, linear or branched, saturated or unsaturated alkoxy chain containing 1 to 40 carbon atoms or linear or branched, saturated or unsaturated oligoethylene glycol chain containing 1 to 40 carbon atoms,'a' is selected as one of 0 or 1.

4. A method according to claim 1, characterized in that said ^-conjugated organic molecule isFormula 2.

5. A method according to claim 1, characterized in that said ^-conjugated organic molecule isFormula 3.

6. A method according to claim 1, characterized in that said ^-conjugated organic molecule isFormula 4.

7. A method according to claim 1, characterized in that said ^-conjugated organic molecule isFormula 5.

8. A method according to claim 1, characterized in that the substrate used in the spin-coating method is silicon-based.

9. A method according to claim 1, characterized in that the solution used in the spin-coating method is chloroform solution.

10. A method according to claim 1, characterized in that the solution used in the spin-coating method is chlorobenzene solution.

11. A crystal obtained by a method according to any one of claims 1-10.

12. A labeling method, characterized in that at least one physical property of the crystal according to claim 11 is measured by at least one sensor and the measurement results from the sensor are converted into a label.

13. A method according to claim 13, characterized in that said sensor measures the fluorescence emission characteristics of the produced crystals.

14. A method according to claim 13, characterized in that said sensor measures the fingerprint molecular vibrations of the crystals produced.

15. A method according to claim 13, characterized in that said sensor detects the morphological characteristics of the microcrystalline formations of the crystals produced.

16. A method according to claim 13, characterized in that said sensor detects the fluorescence microscopy properties of the crystals produced.

17. A method according to claim 13, characterized in that said sensor detects the Raman spectroscopy properties of the crystals produced.

18. A method according to claim 10, characterized in that said sensor detects the optical microscopic properties of the crystals produced.

19. A sensor according to claim 10, characterized in that said sensor detects the dark field microscopy properties of the crystals produced.

Images