Analysis reagent and conformation analysis method for dicarboxylic acid isomer molecules

Abstract

The invention relates to the technical field of chemical analysis, in particular to an analysis reagent for dicarboxylic acid isomer molecules and a conformation analysis method. The method comprises the following steps: dissolving a dicarboxylic acid isomer standard substance to be analyzed in a proper solvent to prepare an isomer dicarboxylic acid solution with a certain concentration, generating isomer dicarboxylic acid gas-phase ions through an ion source, and testing the ion migration characteristics of target gas-phase ions by using an ion mobility spectrometry experimental device. And obtaining the ion mobility spectrometry of the isomer dicarboxylic acid ions. As different isomer dicarboxylic acid molecule ions have different space structures and have different collision interfaces, the conformation of the isomer dicarboxylic acid molecule is obtained according to the obtained ion mobility spectrometry, and the type of the isomer of the dicarboxylic acid molecule is determined. And the molecular structures of different isomer conformations in the sample and the relative content of the isomer molecules with each conformation can be measured at the same time. The analysis method of the isomer dipyridyl dicarboxylic acid molecule is simple in analysis process and high in speed.

Description

Technical Field

[0001] The invention relates to the technical field of chemical analysis, in particular to an analytical reagent and a conformational analysis method for dicarboxylic acid isomer molecules. Background Art

[0002] Isomers are a special type of molecular structure that is commonly found in nature and chemical reactions. They have exactly the same molecular weight, but different positions of substituents or functional groups in the molecule. However, the slight structural differences between isomers can lead to significant differences in their basic physical and chemical properties and functional effects.

[0003] In organic chemistry, isomers are an important concept. Its structure has many forms, each with its own unique properties, some of which may even have a great impact on research or practical applications. Therefore, in a sense, understanding the proportion of compounds with diverse structures in organic matter and the relationship between them is of great significance for understanding the properties of organic matter and guiding organic synthesis. For isomers with diverse structures, in order to better understand their properties and determine their structures, it is necessary to study the relationship between them.

[0004] The dicarboxylic acid molecular isomers are 2,2'-bipyridine-3,3'-dicarboxylic acid (3,3'-BDA) and 2,2'-bipyridine-4,4'-dicarboxylic acid (4,4'-BDA) which are isomers of each other and a pair of isomers are 2,2'-biphenyldicarboxylic acid (2,2'-BA) and 4,4'-biphenyldicarboxylic acid (4,4'-BA).

[0005] Among them, 2,2'-bipyridine-4,4'-dicarboxylic acid is the anchoring ligand that enables the most efficient energy conversion and has important value in photosensitizers. Its complexes with certain metals play an important role in dye-sensitized solar cells and carbon-carbon bond coupling. The catalyst formed by 2,2'-bipyridine-3,3'-dicarboxylic acid as a ligand can effectively reduce the energy barrier of the rate-controlling step in the catalytic reaction and improve the catalytic activity. Due to the many differences in their chemical properties and applications, the accurate analysis and separation of the two isomers has important application value. However, it is precisely because of the structural similarity that identification and separation are challenging and difficult, which makes it one of the most attractive problems in the fields of environment, biology, pharmacology, food science, chemistry and other fields.

[0006] A pair of isomers are 2,2'-biphenyl dicarboxylic acid (2,2'-BA) and 4,4'-biphenyl dicarboxylic acid (4,4'-BA). 2,2'-biphenyl dicarboxylic acid can be used as a raw material for resins and engineering plastics, a modifier for special coatings, a fiber modifier, a special plasticizer, and a pressure-sensitive adhesive modifier. It can also be used as a raw material for rust inhibitors, medicines, dyes, pigments, and pesticides. 4,4'-biphenyl dicarboxylic acid is an important organic synthesis intermediate that can be used in pharmaceuticals and polymer materials. In recent years, it has been widely used in the rapidly developing liquid crystal products. It is also one of the important monomers for synthesizing general-purpose high-performance polymers. The two isomers involve industrial production and pharmaceutical processing, which will have a certain impact on the environment, so it is necessary to separate and identify them to determine their safety. Ion mobility mass spectrometry can efficiently separate the two isomers.

[0007] Mass spectrometry technology is widely used in the precise analysis and measurement of molecules or atoms due to its sensitivity, accuracy and high efficiency, and has been rapidly popularized in various industries, such as medical and health care, food safety, environmental monitoring, industrial analysis, national security and other fields. However, a single mass spectrometry detection can only give the mass-to-charge ratio of a molecule or atom, so it is difficult to measure isomers of the same molecular weight. Ion mobility mass spectrometry is an emerging mass spectrometry analysis technology with the characteristics of high sensitivity, strong selectivity, high resolution and simple operation. Its working principle is to generate sample ions through an electrospray ionization ion source (ESI), and introduce the sample ions into an ion migration tube so that they move in a directional manner under low vacuum conditions and collide with neutral gases. Because the collision cross-sectional area and mobility values ​​of different ions are different, the analysis effect can be achieved by measuring the collision cross-sectional area and mobility value of the sample ions. The particularity of the working principle of this instrument can be used for the measurement and analysis of isomers, and the identification and separation effect can be achieved by comparing the different collision cross-sectional areas and mobility values ​​of isomers.

[0008] Therefore, it is necessary to develop a simple and efficient analytical method for the identification of isomers. Summary of the invention

[0009] The technical problem to be solved by the present invention is: in order to solve the problems existing in the prior art in the above-mentioned background technology, an analytical reagent and a conformational analysis method for dicarboxylic acid isomer molecules are provided.

[0010] The technical solution adopted by the present invention to solve the technical problem is: an analytical reagent for dicarboxylic acid isomer molecules, the analytical reagent comprising a compound of dicarboxylic acid isomer molecules mixed with a solvent.

[0011] Furthermore, the dicarboxylic acid isomer molecules are divided into bipyridine dicarboxylic acid isomer molecules and biphenyl dicarboxylic acid isomer molecules.

[0012] Furthermore, the concentration of biphenyl dicarboxylic acid molecules is between 1 mol / L and 10 -10 mol / L, the concentration of bipyridine dicarboxylic acid molecules is 1mol / L~10 -10 mol / L.

[0013] Furthermore, the solvent is a mixed solution comprising water and one or more other liquids, and the other mixed solution refers to other organic liquids other than water, including but not limited to methanol, ethanol, acetonitrile, ether, acetone, dimethyl sulfoxide and other organic liquid compounds; among two or more liquid compounds, the proportion of each liquid is 0.1% to 99.9%.

[0014] A conformational analysis method for dicarboxylic acid isomer molecules, comprising the following steps:

[0015] Step 1: Adding a solvent to the dicarboxylic acid isomer molecules to be analyzed to prepare a mixture of dicarboxylic acid isomer molecules;

[0016] Step 2: using the mixture obtained in step 1 to generate monovalent gas-phase ions of dicarboxylic acid molecules using an ion source ion generation method;

[0017] Step 3: The positional isomerism information of the dicarboxylic acid molecules can be obtained by measuring the ion mobility spectrum of the dicarboxylic acid ions generated by the dicarboxylic acid molecules using an ion mobility analysis device, or measuring the ion mobility spectrum or ion collision cross section of the monovalent gas-phase ions of the dicarboxylic acid molecules using an ion collision cross section analysis instrument.

[0018] Furthermore, the ion source is an electrospray ionization ion source, a matrix-assisted laser desorption ionization ion source, a DESI ion source or other types of ion sources capable of generating dicarboxylic acid ions from an aqueous solution of a dicarboxylic acid molecule sample and a mixed solution comprising water and other liquids.

[0019] Furthermore, the equipment for ion mobility analysis is an ion mobility spectrometer or includes an ion mobility spectrometer and other instruments.

[0020] The beneficial effects of the present invention are: (1) the compounds used are easy to obtain and cheap;

[0021] (2) The experimental research instruments and methods used are all commercially available and easy to implement;

[0022] (3) No pretreatment is required, the analytical reagents are simple in composition and easy to prepare;

[0023] (4) The analytical method is easy to operate and implement, has no complicated steps, and has fast analysis speed and good accuracy;

[0024] (5) The different structures of multiple isomers in a mixture can be analyzed simultaneously with accurate quantification, without the need for complex pre-separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1 Schematic diagram of the molecular structure of two isomers of bipyridine dicarboxylic acid molecules of the present invention;

[0027] Figure 2 is a mass spectrum of the bipyridine dicarboxylate ion of the present invention;

[0028] Figure 3 It is a graph showing the experimental results of ion migration spectra of two bipyridine dicarboxylic acid ions of the present invention;

[0029] Figure 4 It is a schematic diagram of the molecular structure of two isomers of biphenyl dicarboxylic acid molecules of the present invention;

[0030] Figure 5 is the mass spectrum of the biphenyl dicarboxylate ion of the present invention;

[0031] Figure 6 It is a graph showing the experimental results of ion migration spectra of two biphenyl dicarboxylic acid ions of the present invention. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0033] Embodiment 1:

[0034] like Figures 1 to 3 As shown in Table 1, the dicarboxylic acid isomer molecules are divided into bipyridine dicarboxylic acid isomer molecules. The types of bipyridine dicarboxylic acid molecules subjected to isomer analysis are 2,2'-bipyridine-3,3'-dicarboxylic acid (3,3'-BDA) and 2,2'-bipyridine-4,4'-dicarboxylic acid (4,4'-BDA), as shown in Table 1.

[0035] Table 1 List of bipyridine dicarboxylic acid molecules analyzed by the method of the present invention for molecular isomers

[0036]

[0037] First, an appropriate amount of the bipyridine dicarboxylic acid isomer sample to be analyzed is weighed, completely dissolved in dimethyl sulfoxide, and diluted to a concentration of 10-5 mol / L using a methanol: water mixed solution (CH3OH:H2O=1:1) to prepare a bipyridine dicarboxylic acid isomer solution of a certain concentration;

[0038] Then, the TIMS-TOFMS instrument produced by Bruke was used to conduct tests. The specific experimental process was to use the electrospray ionization (ESI) ion source of the TIMS-TOFMS instrument to generate isomers of bipyridine dicarboxylic acid gas phase ions, and mass spectrometry was used to analyze the various ion products generated by ESI ( Figure 2 Schematic diagram of mass spectrometry results obtained in one experiment);

[0039] Then, the ion migration characteristics of the target gas phase ions were further tested using an ion migration spectrometer. This instrument analyzes the ion migration spectrum of the monovalent ion (m / e=245.06) of the target sample (e.g. Figure 3 As shown in the figure, since different isomers of bipyridine dicarboxylic acid molecular ions have different spatial structures, their collision interfaces are different, that is, they show different ion migration characteristics, that is, different ion mobilities. Therefore, the conformation of the isomer bipyridine dicarboxylic acid molecule can be obtained according to the obtained ion migration spectrum, and the isomer types of the bipyridine dicarboxylic acid molecule can be determined.

[0040] Since [3,3'-BDA+H]+ and [4,4'-BDA+H]+ ions have different collision cross sections; therefore, different ion mobilities, through comparative analysis, we obtain the isomeric structure of the analyzed bipyridine dicarboxylic acid, i.e., BDA, i.e., whether it is 3,3'-BDA or 4,4'-BDA.

[0041] This method can also simultaneously determine the molecular structures of different isomeric conformations in a sample, as well as the relative content of isomeric molecules with each conformation.

[0042] During the experiment, the type and relative content of the solvent used to prepare the solution can be as needed, that is, it can be a mixture of water and dimethyl sulfoxide, a mixture of water and methanol, or a mixture of any two or more commonly used reagents such as water, methanol, ethanol, acetonitrile, acetone, etc., and the proportion of various reagents in the mixed solution is not limited and is determined according to experimental needs.

[0043] In addition, suitable ion generating devices, such as electrospray ionization ion source, matrix-assisted laser desorption ionization ion source, or DESI ion source, can be other types of ion sources capable of generating bipyridine dicarboxylic acid ions from aqueous solutions of bipyridine dicarboxylic acid molecular samples and mixed solutions including water and other liquids.

[0044] In summary, the solution for analyzing the isomer structure of bipyridine dicarboxylic acid molecules provided by the present invention has a simple composition, is easy to obtain, and has low cost. It can be combined with existing experimental methods to achieve rapid analysis of the isomer structure of bipyridine dicarboxylic acid molecules and obtain the isomer structure information of bipyridine dicarboxylic acid molecules.

[0045] Embodiment 2:

[0046] like Figures 4 to 6 As shown in Table 2, dicarboxylic acid isomer molecules are divided into biphenyl dicarboxylic acid isomer molecules. The types of biphenyl dicarboxylic acid molecules that can be subjected to isomer analysis are 2,2'-biphenyl dicarboxylic acid (2,2'-BA) and 4,4'-biphenyl dicarboxylic acid (4,4'-BA), as shown in Table 2.

[0047] Table 2 List of biphenyl dicarboxylic acid molecules analyzed by the method of the present invention for molecular isomers

[0048]

[0049] First, weigh an appropriate amount of biphenyl dicarboxylic acid isomer samples to be analyzed on an analytical balance, completely dissolve them with dimethyl sulfoxide, and dilute them to 10-5 mol / L using a methanol: water mixed solution (CH3OH:H2O=1:1) (the concentration of the sample is not limited, and the preferred concentration is 10-5 mol / L);

[0050] Then, the TIMS-TOFMS instrument produced by Bruke was calibrated (instrument parameters were electrospray ion source: negative ion mode; sample injection flow rate: 5 μL / min; drying gas temperature: 200°C; electrospray voltage: 4500 V; drying gas flow rate: 3.0 L / min);

[0051] The sample was then tested. The specific experimental process was to use the electrospray ionization (ESI) ion source of the TIMS-TOFMS instrument to generate the monovalent anion of the bipyridine isomer, namely [BA-H] - , and mass spectrometry analysis of various ion products produced by ESI ( Figure 5 Schematic diagram of mass spectrometry results obtained in one experiment);

[0052] Then, the instrument is further used to analyze the ion mobility spectrum of the monovalent ion (m / e=241.01) of the target sample (e.g. Figure 6 As shown in the figure, we can obtain different structural information of the two biphenyl dicarboxylic acid molecules. Since [2,2'-BA-H]- and [4,4'-BA-H]- ions have different collision cross sections and therefore different ion mobilities, we can obtain the analyzed biphenyl dicarboxylic acids and distinguish 2,2'-BA from 4,4'-BA through comparative analysis.

[0053] During the experiment, the type and relative content of the solvent used to prepare the solution can be prepared as needed, that is, it can be a mixture of water and dimethyl sulfoxide, or a mixture of water and methanol, or a mixture of any two or more commonly used reagents such as water, methanol, ethanol, acetonitrile, acetone, etc., and the proportion of various reagents in the mixed solution is not limited and is determined according to experimental needs as long as the biphenyl dicarboxylic acid sample can be completely dissolved.

[0054] In addition, suitable ion generating devices, such as electrospray ionization ion source, matrix-assisted laser desorption ionization ion source, or DESI ion source, may be other types of ion sources capable of generating biphenyl dicarboxylic acid ions from aqueous solutions of biphenyl dicarboxylic acid molecule samples and mixed solutions including water and other liquids.

[0055] In summary, the solution composition for analyzing the isomer structure of biphenyl dicarboxylic acid molecules provided by the present invention is simple, easy to obtain, low in cost, and can be combined with existing experimental methods to achieve rapid analysis of the isomer structure of biphenyl dicarboxylic acid molecules and obtain isomer structure information of biphenyl dicarboxylic acid molecules. The method provided by the present invention can also obtain information on their relative contents. The present invention does not require complex processing, is efficient and simple, and has obvious advantages compared to current isomer analysis methods.

[0056] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An analytical reagent for dicarboxylic acid isomer molecules, Features: The analytical reagent comprises a compound of dicarboxylic acid isomer molecules mixed with a solvent.

2. An analytical reagent for dicarboxylic acid isomer molecules according to claim 1, Features: The dicarboxylic acid isomer molecules are divided into bipyridine dicarboxylic acid isomer molecules and biphenyl dicarboxylic acid isomer molecules.

3. An analytical reagent for dicarboxylic acid isomer molecules according to claim 2, Features: The concentration of the biphenyl dicarboxylic acid molecules is between 1 mol / L and 10 -10 mol / L, the concentration of bipyridine dicarboxylic acid molecules is 1mol / L~10 - 10 mol / L.

4. An analytical reagent for dicarboxylic acid isomer molecules according to claim 2, Features: The solvent is a mixed solution containing water and one or more other liquids. The other mixed solution refers to other organic liquids other than water, including but not limited to methanol, ethanol, acetonitrile, ether, acetone, dimethyl sulfoxide and other organic liquid compounds; among the two or more liquid compounds, the proportion of each liquid is 0.1% to 99.9%.

5. A conformational analysis method for dicarboxylic acid isomer molecules, Features: The following steps are involved: Step 1: Adding a solvent to the dicarboxylic acid isomer molecules to be analyzed to prepare a mixture of dicarboxylic acid isomer molecules; Step 2: using the mixture obtained in step 1 to generate monovalent gas-phase ions of dicarboxylic acid molecules using an ion source ion generation method; Step 3: The positional isomerism information of the dicarboxylic acid molecules can be obtained by measuring the ion mobility spectrum of the dicarboxylic acid ions generated by the dicarboxylic acid molecules using an ion mobility analysis device, or measuring the ion mobility spectrum or ion collision cross section of the monovalent gas-phase ions of the dicarboxylic acid molecules using an ion collision cross section analysis instrument.

6. A method for conformational analysis of dicarboxylic acid isomer molecules according to claim 5, Features: The ion source is an electrospray ionization ion source, a matrix-assisted laser desorption ionization ion source, a DESI ion source or other types of ion sources capable of generating dicarboxylic acid ions from an aqueous solution of a dicarboxylic acid molecule sample and a mixed solution of water and other liquids.

7. A method for conformational analysis of dicarboxylic acid isomer molecules according to claim 5, Features: The equipment for ion mobility analysis is an ion mobility spectrometer or includes an ion mobility spectrometer and other instruments.

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