Sensors for detecting gas analytes

Abstract

A sensor and a method for using the sensor are disclosed. The sensor includes a conductive region electrically connected to two electrodes, the conductive region including metal nanowires, nanosized particles of dichalcogenides, and a mercaptoimidazole-based metal-ligand complex. The sensor can be used to detect volatile compounds having double or triple bonds.

Description

background

[0001] Exemplary embodiments relate to technology for metal complex-based sensor compositions.

[0002] Volatile compounds with double or triple bonds form an important group of compounds for detection. In particular, volatile olefins (e.g., ethylene) are analytes of considerable importance. In particular, the detection of ethylene is important for industries related to production and agriculture. However, due to its small size and limited chemical functionality, ethylene is a challenging chemical analyte to detect. More effective and sensitive detection methods are needed than those currently available. Brief description of the invention

[0003] A sensor is disclosed that includes a conductive region in electrical communication with two electrodes, the conductive region including metal nanowires, nanosized particles of metal dichalcogenides, and a mercaptoimidazole-based metal-ligand complex.

[0004] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the nanosized particles of metal dichalcogenides include MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, and combinations thereof.

[0005] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes more than one mercaptoimidazolyl group.

[0006] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes three mercaptoimidazolyl groups.

[0007] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes a pyrazolyl or indolyl group in addition to the mercaptoimidazolyl group.

[0008] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazole metal-ligand complex includes Cu(I), Ag(I), or Au(I).

[0009] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the mercaptoimidazolyl metal-ligand complex is a complex of formula (II):

[0010]

[0011] Therein, R1 and R2 may in each case be hydrogen or a radical comprising one or more carbon atoms.

[0012] Also disclosed is a method for sensing volatile compounds having double or triple bonds, the method comprising exposing a sensor to a sample, the sensor comprising a conductive region electrically connected to two electrodes, the conductive region comprising metal nanowires, nanosized particles of metal dichalcogenides, and a mercaptoimidazole metal-ligand complex, and measuring electrical properties at the electrodes.

[0013] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the electrical property is conductivity.

[0014] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the electrical property is resistivity.

[0015] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the method further comprises comparing the electrical property value obtained by measurement with a calibration curve to determine the amount of volatile compounds having double or triple bonds present in the sample.

[0016] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the volatile compound having a double bond or a triple bond is ethylene.

[0017] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the nanosized particles of metal dichalcogenides include MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, and combinations thereof.

[0018] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes more than one mercaptoimidazolyl group.

[0019] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes three mercaptoimidazolyl groups.

[0020] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazolyl metal-ligand complex includes a pyrazolyl or indolyl group in addition to the mercaptoimidazolyl group.

[0021] In addition to one or more of the above features, or as an alternative to any of the preceding embodiments, the mercaptoimidazole metal-ligand complex includes Cu(I), Ag(I), or Au(I).

[0022] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the mercaptoimidazolyl metal-ligand complex is a complex of formula (II):

[0023]

[0024] Therein, R1 and R2 may in each case be hydrogen or a radical comprising one or more carbon atoms.

[0025] In another aspect, a method of making a sensor includes forming a conductive region comprising metal nanowires, nanosized particles of metal dichalcogenide, and a mercaptoimidazole-based metal-ligand complex, and placing the conductive region in electrical communication with two electrodes. Detailed Description

[0026] By way of example and not limitation, a detailed description of one or more embodiments of the disclosed apparatus and methods is presented herein.

[0027] Volatile compounds with double or triple bonds are an important group of compounds for detection and monitoring. As used herein, the term volatility refers to compounds that are in the gas phase at standard temperature and pressure. Exemplary compounds include NO2, CO2, CO, and olefins such as C2H4 (ethylene). As a hormone responsible for initiating fruit ripening and other processes in plant development, ethylene is an analyte of considerable importance to industries related to production and agriculture. Due to its small size and limited chemical functionality, ethylene and other volatile olefins are chemicals that are challenging to detect. Sensors and methods capable of detecting volatile compounds with double bonds (such as ethylene and other volatile olefins) at levels as low as 100 parts per billion (ppb) are disclosed herein.

[0028] The sensor includes a conductive region in electrical communication with at least two electrodes. The conductive region includes metal nanowires, nano-sized particles of metal dichalcogenides, and a mercaptoimidazole-based metal-ligand complex.

[0029] Metal nanowires are known materials and are commercially available. The nanowires may have a width of 10 nanometers to 1 micron and may have a length of 10 microns to 1 millimeter or longer. The nanowires may have a length: width ratio greater than 1000. The nanowires may include one or more elements from Groups 1 to 12 and Al, Ga, In, Sn, Tl, Pb, and Bi. In some embodiments, the metal nanowires include one or more of Ni, Cu, Au, Pt, or Ag. The preparation method of the nanowires is described in U.S. Patent No. 6,843,902.

[0030] Metal dichalcogenides include transition metal dichalcogenides, which are compounds formed from Group 6B metals and chalcogenides (S, Se, and Te). Exemplary metal dichalcogenides include MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, and combinations thereof. The metal dichalcogenides are in the form of nano-sized particles. "Nano-sized" when applied to metal dichalcogenides refers to the fact that the thickness of the material is less than or equal to 100 nanometers. Metal dichalcogenides are generally available in the form of flakes having a thickness of 100 nanometers or less, but other physical forms are not excluded, and it should be noted that the physical form has a linear dimension less than or equal to 100 nanometers.

[0031] The mercaptoimidazolyl metal-ligand complex is a multidentate coordination complex comprising one or more mercaptoimidazolyl groups. The arms (groups on the boron atom) of the multidentate ligand may be the same (homoleptic) or different (heteroleptic). For example, one arm may comprise a mercaptoimidazolyl group and the second arm may comprise a pyrazolyl or indolyl group. It is also contemplated that the multidentate ligand may comprise more than one mercaptoimidazolyl group or a mercaptoimidazolyl group and a pyrazolyl or indolyl group or a combination of the two. The mercaptoimidazolyl metal-ligand complex may have formula (I)

[0032]

[0033] Wherein, R1 and R2 may be hydrogen or a group having one or more carbons in each case. In some embodiments, R1 and R2 may be hydrogen or an alkyl group having 1-5 carbons in each case. L in formula (I) may be pyrazolyl, mercaptoimidazolyl or indolyl. When L is mercaptoimidazolyl, the multidentate metal-ligand complex may be described as homogeneous. When L is a group other than mercaptoimidazolyl, the metal-ligand complex may be described as heterogeneous. The presence of VOC in formula (I) is to show the hypothetical interaction with volatile compounds having π bonds. Without being bound by theory, it is believed that the π bonds of volatile compounds coordinate with empty coordination sites on the metal-ligand complex. The coordination changes the electronic configuration of the complex and may affect the electrical properties of the combination of metal-ligand complexes, nanosized particles of metal dichalcogenides and metal nanowires. In the case of a metal complex having formula (II) shown below, when the metal complex is combined with ethylene, the resistivity of a combination of the metal-ligand complex, nanosized particles of metal dichalcogenide, and metal nanowires increases.

[0034] A more specific example of the mercaptoimidazolyl metal complex is represented by formula (II).

[0035]

[0036] In formula (II) there are three mercaptoimidazole groups. R1 and R2 are as defined in formula (I).

[0037] The metal in the mercaptoimidazole metal complex may include Group 11 elements such as Cu(I), Ag(I) and Au(I).

[0038] The metal nanowires and nanosized particles of metal dichalcogenides are applied to a substrate. The substrate may be a flexible polymer film or other suitable material. Exemplary flexible polymer films include polyethylene terephthalate, polyethylene, polypropylene, polyamide, and polyvinyl chloride. Prior to applying the metal nanowires and nanosized particles of metal dichalcogenides, an electrode may be deposited on the substrate. The metal nanowires and metal dichalcogenide particles may be applied by spray deposition. These materials may be co-deposited or deposited sequentially. After the metal nanowires and nanosized particles of metal dichalcogenides are applied to the substrate, the mercaptoimidazole-based metal complex is deposited on the metal nanowires and nanosized particles of metal dichalcogenides. The mercaptoimidazole-based metal complex may be applied by drop casting, dip coating, spray coating, or electrospraying. The layered material is then dried and ready for use.

[0039] A method of sensing a volatile compound having a double or triple bond comprises exposing a sensor as described above to a sample and measuring an electrical property of a two-electrode system. The electrical property may be conductivity or resistivity. The method may further comprise comparing the electrical property value obtained with a calibration curve to determine the amount of the volatile compound present in the sample.

[0040] The terms used herein are used only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0041] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present disclosure without departing from the substantive scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed as the best mode for implementing the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A sensor comprising a conductive region electrically connected to two electrodes, wherein the conductive region comprises metal nanowires, nanosized particles of metal dichalcogenides and a mercaptoimidazole-based metal complex, wherein the mercaptoimidazole-based metal complex is a homoleptic complex of formula (II): in, R1 and R2 are in each case hydrogen or an alkyl radical having 1 to 5 carbons.

2. The sensor of claim 1, wherein the nanosized particles of metal dichalcogenides comprise MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, and combinations thereof.

3. A method for sensing a volatile compound having a double bond or a triple bond, the method comprising exposing a sensor to a sample, the sensor comprising a conductive region electrically connected to two electrodes, the conductive region comprising metal nanowires, nanosized particles of metal dichalcogenides and a mercaptoimidazolyl metal-ligand complex, and measuring electrical properties at the electrodes, wherein the mercaptoimidazolyl metal complex is a homoleptic complex of formula (II): in, R1 and R2 are in each case hydrogen or an alkyl radical having 1 to 5 carbons. 4 . The method according to claim 3 , further comprising comparing the electrical property value obtained by the measurement with a calibration curve to determine the amount of the volatile compound having a double bond or a triple bond present in the sample. The method according to claim 4 , wherein the volatile compound having a double bond or a triple bond is ethylene.

6. The method of any one of claims 3-5, wherein the nanosized particles of metal dichalcogenide comprise MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, and combinations thereof.

7. A method for preparing a sensor, the method comprising forming a conductive region, the conductive region comprising metal nanowires, nanosized particles of metal dichalcogenides and a mercaptoimidazole-based metal-ligand complex, and placing the conductive region in electrical communication with two electrodes, wherein the mercaptoimidazole-based metal complex is a homoleptic complex of formula (II): in, R1 and R2 are in each case hydrogen or an alkyl radical having 1 to 5 carbons.

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