Process for the generation of similar metal alkoxide or metal carboxylate molecular clusters based on general structural features

Abstract

The application discloses a method for generating similar metal alkoxide or metal carboxylate molecular clusters based on general structural characteristics. Firstly, the potential energy surface of the selected metal alkoxide or metal carboxylate molecular cluster is globally searched to obtain a stable configuration. Then, the density functional theory is used to perform structural optimization and vibration frequency analysis. The balanced structure with all real frequencies of vibration is screened out. The energy minimum point is confirmed. Energy calculation is performed. Finally, the cluster configuration with the lowest energy is selected. Secondly, the characteristic complexation mode of the obtained cluster configuration with the lowest energy is analyzed. Two efficient structure prediction methods, namely, center metal replacement method and surrounding carbon chain replacement method, are proposed. Both methods allow replacement of metal ions or carbon chain groups to generate a series of possible stable cluster structures under the premise of maintaining the basic cluster configuration and hydrogen bond network. Further, the new structures obtained are verified through density functional theory optimization calculation, so that the target cluster configuration is quickly obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of molecular cluster structure prediction, and particularly relates to a high-efficiency generation method of similar metal alkoxide or metal carboxylate molecular clusters based on general structural features. BACKGROUND

[0002] Metal alkoxide and metal carboxylate molecular clusters have important application value in the fields of catalysis, material science, biomedicine and the like. The research on the cluster structures is of great significance for understanding their physical and chemical properties and developing new functional materials.

[0003] Global optimization of cluster structures is a great challenge in current computational chemistry research, mainly because the coordination mode and molecular orientation inside the cluster have a significant impact on its energy, making it difficult to accurately locate the most stable configuration corresponding to the global energy minimum. Although a variety of global optimization algorithms have been developed, such as genetic algorithm, particle swarm optimization, artificial bee colony algorithm, etc., for cluster structure search, these methods still have limitations when facing different types of metal alkoxide or metal carboxylate molecular clusters. In particular, different types of metals, alcohols and carboxylic acids will lead to changes in the structure of complex clusters. If each combination of metal alkoxide or metal carboxylate molecular clusters is independently searched from scratch, the efficiency of structure prediction will inevitably be greatly reduced.

[0004] In addition, existing research pays little attention to the regularity of the mutual complexation mode of metal alkoxide and alcohol molecules or metal carboxylate and carboxylic acid molecules in metal alkoxide or metal carboxylate molecular clusters, and lacks effective methods for using known structural information to guide the prediction of new structures. SUMMARY

[0005] The application provides a high-efficiency generation method of similar metal alkoxide or metal carboxylate molecular clusters based on general structural features, which is a method capable of quickly and efficiently predicting and generating stable structures of similar metal alkoxide or metal carboxylate molecular clusters, reducing computational cost and improving structure prediction efficiency.

[0006] The application proposes two high-efficiency structure prediction methods based on central metal replacement and surrounding carbon chain replacement by in-depth analysis of the structural features of known stable cluster configurations, which can significantly improve the generation efficiency of similar cluster structures and provide a new technical approach for related research.

[0007] A high-efficiency generation method of similar metal alkoxide or metal carboxylate molecular clusters based on general structural features, comprising the following steps:

[0008] Step one, performing global search on the potential energy surface of the selected metal alkoxide or metal carboxylate to obtain stable configurations for preliminary screening;

[0009] Subsequently, the density functional theory method is used to perform structural optimization on the preliminary candidate configuration set, vibration frequency analysis is performed on the optimized structure, the balanced structure with all real frequencies is selected from the optimized structure, it is confirmed that the balanced structure is at the energy minimum point, and energy calculation is performed, and finally the cluster configuration with the lowest energy is selected;

[0010] Step two, analyze the lowest energy cluster configuration obtained, and summarize the mutual complexation mode of metal alkoxide and alcohol molecules or metal carboxylate and carboxylic acid molecules in the cluster;

[0011] Step three, according to the mutual complexation mode of metal alkoxide molecules and alcohol molecules in the cluster, replace the metal ion with other metal ions in the same main group, or / and replace the carbon chain in the alkoxy ion and alkoxy group with a C1 to C5 straight carbon chain;

[0012] According to the mutual complexation mode of metal carboxylate molecules and carboxylic acid molecules in the cluster, replace the metal ion with other metal ions in the same main group, or / and replace the carbon chain in the acyloxy ion and acyloxy group with a C1 to C5 straight carbon chain;

[0013] Finally, the structure after replacement is obtained.

[0014] Step four, using the density functional theory method, the structure after replacement is optimized, vibration frequency analysis is performed on the optimized structure, and finally energy calculation is performed to obtain similar metal alkoxide or metal carboxylate molecular cluster structure.

[0015] In step one, the global search adopts the ABCluster global optimization program package.

[0016] In steps one and three, the Gaussian quantum chemistry calculation program or the ORCA quantum chemistry calculation program is used to perform structural optimization, vibration frequency analysis, and finally energy calculation.

[0017] In step two, the mutual complexation mode of metal alkoxide molecules and alcohol molecules in the cluster specifically includes:

[0018] The metal alkoxide molecules in the inner layer contain metal ions and alkoxy ions, and the metal ions and alkoxy ions are connected in the form of ionic bonds;

[0019] The alcohol molecules in the outer layer are arranged around the inner layer metal alkoxide molecules through a hydrogen bond network, the alcohol molecules contain alkoxy groups, and the carbon chain of the alkoxy group extends outward in the direction away from the metal carboxylate molecule.

[0020] In step two, the mutual complexation mode of metal carboxylate molecules and carboxylic acid molecules in the cluster specifically includes:

[0021] As the metal carboxylate salt molecule of the inner layer, the metal carboxylate salt molecule contains metal ions and acyloxy ions, and the metal ions and the acyloxy ions are connected in the form of ionic bonds;

[0022] As the carboxylic acid molecule of the outer layer, the carboxylic acid molecule is arranged around the metal carboxylate salt molecule of the inner layer through a hydrogen bond network, and the carboxylic acid molecule contains an acyloxy group, and the carbon chain of the acyloxy group extends outward in a direction away from the metal carboxylate salt molecule.

[0023] In step three, the replacement of the metal ion with other metal ions in the same main group is performed by using the Materials Studio molecular modeling software, the GaussView molecular modeling software, the RDKit molecular modeling package or the OpenBabel molecular modeling package.

[0024] In step three, the replacement of the carbon chain in the alkoxy group or the acyloxy group with other straight carbon chains in the C1 to C5 straight carbon chain is performed by using the RDKit molecular modeling package or the OpenBabel molecular modeling package.

[0025] Specifically, an efficient generation method of similar metal alkoxide or metal carboxylate salt molecular clusters based on general structural characteristics, the generation method comprising:

[0026] Step one, a global search is performed on the potential energy surface of the selected metal alkoxide or metal carboxylate salt to obtain a preliminary candidate configuration set. Subsequently, the density functional theory method is used to first perform structure optimization on the candidate configuration, and then perform vibration frequency analysis on the optimized structure, confirm that the equilibrium structure with all real frequencies is at the energy minimum point by screening out the equilibrium structure with all real frequencies, and finally select the cluster configuration with the lowest energy by performing energy calculation;

[0027] Step two, by systematically analyzing the obtained cluster configuration with the lowest energy, the mutual complexation mode of the metal alkoxide and the alcohol molecule or the metal carboxylate salt and the carboxylic acid molecule in the cluster is summarized: the metal alkoxide or the metal carboxylate salt molecule constitutes the inner layer structure of the cluster, wherein the metal alkoxide contains metal ions and alkoxy ions, or the metal carboxylate salt molecule contains metal ions and acyloxy ions, and the oxygen atoms in the metal ions and the alkoxy ions or the acyloxy ions are used as the central region of the cluster; the above metal alkoxide or metal carboxylate salt molecule is surrounded by corresponding alcohol molecules or carboxylic acid molecules, and these outer alcohol molecules or carboxylic acid molecules form an ordered hydrogen bond network through hydroxyl groups, and the carbon chains thereof extend outward to the outside of the cluster. Based on this structural characteristic, the present application proposes two efficient structure prediction methods:

[0028] (1) Center metal replacement method: This method replaces the metal ion in the metal alkoxide or metal carboxylate molecule with other metal ions in the same main group while maintaining the overall configuration of the cluster and the skeleton of the hydrogen bond network. Because metal elements in the same main group have similar outer electron configurations and chemical properties, such replacement can maintain the basic structural characteristics of the cluster while obtaining a series of possibly more stable cluster structures;

[0029] (2) Surrounding carbon chain replacement method: This method replaces the carbon chain in the alkoxy ion, alkoxy group or acyloxy ion, acyloxy group with a C1 to C5 straight carbon chain while maintaining the center of the cluster and the surrounding hydrogen bond network. Because the carbon chain part in the cluster structure extends outward, changing its carbon chain length has little effect on the center of the cluster and the hydrogen bond network, so the basic configuration characteristics of the cluster can be maintained while obtaining a series of homologous cluster structures with different carbon chain lengths.

[0030] For the new structures obtained by the above methods, density functional theory optimization calculation is performed again, that is, stable target cluster configurations can be quickly obtained.

[0031] The composition of the metal alkoxide or metal carboxylate molecular cluster satisfies the following conditions:

[0032] (1) The cluster contains only one metal alkoxide or metal carboxylate molecule as the core;

[0033] (2) The remaining molecules in the cluster are alcohol molecules or carboxylic acid molecules corresponding to the core;

[0034] (3) The metal alkoxide, alcohol molecule or metal carboxylate, carboxylic acid molecule all contain C1 to C5 straight carbon chains;

[0035] The specific implementation steps of the center metal replacement method in step two include:

[0036] (1) Based on the known stable metal alkoxide or metal carboxylate molecular structure, identify and locate the metal ion; and based on the periodic table, select other metal elements in the same main group as the original metal ion;

[0037] (2) Use molecular modeling software (such as Materials Studio, GaussView, etc.) or molecular modeling program package (such as RDKit, OpenBabel, etc.) to replace the metal ion with the selected metal element in the same main group, while maintaining the overall structure and coordination geometry of the cluster;

[0038] (3) Perform density functional theory structure optimization on the newly generated structure;

[0039] The specific implementation steps of the carbon chain deletion in the surrounding carbon chain replacement method in step two include:

[0040] (1) Using molecular modeling packages (such as RDKit, OpenBabel, etc.), on the basis of known stable metal alkoxide or metal carboxylate molecular cluster structures, by removing methyl (-CH3) or other appropriate hydrocarbon units at the end of the carbon chain (the end opposite to the hydroxyl group) of the alkoxy ion, alkoxy group or acyloxy ion, acyloxy group, the gradual shortening of the carbon chain is realized;

[0041] (2) The new generated structure is subjected to density functional theory structure optimization;

[0042] In the specific implementation of the surrounding carbon chain replacement method described in step two, considering that the extension of the carbon chain may lead to an increase in steric hindrance, thereby affecting the stability of the cluster structure and deviating from the global minimum value of the potential energy surface, the present application designs the following structure generation process, specifically including:

[0043] (1) Using molecular modeling packages (such as RDKit, OpenBabel, etc.), on the basis of known stable metal alkoxide or metal carboxylate molecular structures, by replacing any one hydrogen atom with a methyl (-CH3) or other appropriate hydrocarbon unit at the end of the carbon chain (the end opposite to the hydroxyl group) of the alkoxy ion, alkoxy group or acyloxy ion, acyloxy group, the gradual extension of the carbon chain is realized, wherein the structure parameters such as the dihedral angle and bond angle of the carbon chain skeleton of the extension configuration can refer to the eigenvalues of the corresponding monomer molecular energy minimum configuration, thereby generating a series of candidate configurations;

[0044] (2) The generated candidate structures are subjected to preliminary screening: first, eliminate configurations with atomic distance less than the sum of van der Waals radii; then randomly select one-third of the candidate configurations from the remaining configurations for preliminary energy calculation using the GFNn-xTB semi-empirical quantum chemistry method, and select an appropriate number of low-energy configurations as initial configurations;

[0045] (3) The obtained initial configurations are subjected to density functional theory structure optimization to determine the final stable configuration.

[0046] In step one, the ABCluster global optimization package is used to perform global search and configuration sampling on the potential energy surface of the metal alkoxide or metal carboxylate molecular cluster to obtain a preliminary candidate configuration set;

[0047] In step two, the GFNn-xTB semi-empirical quantum chemistry method of the xTB semi-empirical quantum chemistry program is used for preliminary energy calculation;

[0048] Using the density functional theory method, the obtained configurations are subjected to structure optimization and vibration frequency analysis by quantum chemistry calculation programs such as Gaussian or ORCA.

[0049] Compared with the prior art, the present application has the following advantages:

[0050] The method of the present application comprises two main steps: firstly, a global search is performed on the potential energy surface of the selected metal alkoxide or metal carboxylate molecular cluster to obtain a preliminary candidate configuration set, and then, the density functional theory method is used to firstly perform structure optimization on the preliminary candidate configuration set, and then perform vibration frequency analysis on the optimized structure, select the equilibrium structure with all real frequencies from the optimized structure, confirm that the equilibrium structure is at the energy minimum point, and perform energy calculation, and finally select the cluster configuration with the lowest energy. Secondly, the characteristic complexation mode of the obtained lowest energy cluster configuration is analyzed, and two efficient structure prediction methods are proposed: center metal replacement method and surrounding carbon chain replacement method. Both of the two methods allow the replacement of metal ions or carbon chain groups while maintaining the basic configuration of the cluster and the hydrogen bond network, so as to generate a series of possible stable cluster structures. Further, the new structures obtained are verified through density functional theory optimization calculation, so as to quickly obtain the target cluster configuration. Compared with the traditional method, the present application significantly improves the efficiency, because after obtaining a specific metal alkoxide or metal carboxylate molecular cluster structure, the molecular cluster of the same main group metal or the homologous molecular cluster of the same metal but with different carbon chain lengths can be quickly expanded, without the need to perform complete potential energy surface global search from the beginning for each cluster, so that the calculation cost can be significantly reduced. At the same time, the present application performs configuration prediction under the premise of maintaining the basic configuration of the cluster and the hydrogen bond network, fully utilizes the structure information of the obtained lowest energy stable configuration, and improves the accuracy of subsequent structure prediction.

[0051] The method can be widely applied to the research of metal alkoxide and metal carboxylate related molecular clusters, and provides an important basis for material design and chemical reaction mechanism research. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 : Schematic diagram of the specific technical approach of the present application;

[0053] Figure 2 : Schematic diagram of the center metal replacement method in the present application;

[0054] Figure 3 : Schematic diagram of the surrounding carbon chain replacement method in the present application;

[0055] Figure 4 : Comparison diagram of the stable configurations of lithium acetate·acetic acid clusters (C2H3O2Li·(C2H4O2)4) obtained by the two methods (center metal replacement method vs. global search) in Example 1 of the present application;

[0056] Figure 5: In the embodiment two of the present application, the contrast chart of stable configurations of potassium ethoxide·ethanol cluster (C2H5OK·(C2H5OH)6) obtained by two methods (central metal replacement method vs global search) is shown;

[0057] Figure 6 : In the embodiment three of the present application, the contrast chart of stable configurations of sodium methoxide·methanol cluster (CH3ONa·(CH3OH)7) obtained by two methods (surrounding carbon chain replacement method vs global search) is shown;

[0058] Figure 7 : In the embodiment four of the present application, the contrast chart of stable configurations of sodium propanol cluster (C3H7ONa·(C3H7OH)6) obtained by two methods (surrounding carbon chain replacement method vs global search) is shown;

[0059] Figure 8 : In the embodiments one to four of the present application, the contrast chart of molecular cluster energy obtained by two methods (central metal replacement method vs global search) and (surrounding carbon chain replacement method vs global search) is shown. DETAILED DESCRIPTION

[0060] The specific embodiments of the present application are further described in detail below, but the present application is not limited to these embodiments, and any improvement or replacement in the basic spirit of the present embodiments still belongs to the scope of protection claimed by the present application.

[0061] As shown in Figure 1 , a high-efficiency generation method of similar metal alkoxide or metal carboxylate molecular cluster based on general structural characteristics, the generation method comprises:

[0062] Step one, performing global search on the potential energy surface of a selected metal alkoxide or metal carboxylate molecular cluster to obtain a preliminary candidate configuration. Then, using the density functional theory method, the candidate configuration is first subjected to structure optimization, and then the optimized structure is subjected to vibration frequency analysis, the equilibrium structure with all vibration frequencies being real frequencies is screened out to confirm that it is at the energy minimum point, and energy calculation is performed, and finally the cluster configuration with the lowest energy is selected;

[0063] Step two, the lowest energy cluster configuration obtained by system analysis, found that it has the following characteristics of complex mode: metal alkoxide or metal carboxylate molecules constitute the inner structure of the cluster, wherein the metal alkoxide contains metal ions and alkoxide ions, or the metal carboxylate molecule contains metal ions and acyloxy ions, with the oxygen atoms in the metal ions and alkoxide ions or acyloxy ions as the cluster center region; The above metal alkoxide or metal carboxylate molecule is surrounded by corresponding alcohol molecules or carboxylic acid molecules, and these outer layer alcohol molecules or carboxylic acid molecules form an ordered hydrogen bond network through the hydroxyl group, and the carbon chain extends to the outside of the cluster. Based on this structural feature, the present application proposes two efficient structure prediction methods:

[0064] (1) As shown in Figure 2 , the central metal replacement method: this method replaces the metal ion in the metal alkoxide or metal carboxylate molecule with other metal ions in the same group on the basis of maintaining the overall configuration of the cluster and the skeleton of the hydrogen bond network. Because metal elements in the same group have similar outer electron configurations and chemical properties, such replacement can obtain a series of stable molecular cluster structures of metal elements in the same group while maintaining the basic structural characteristics of the cluster;

[0065] (2) As shown in Figure 3 , the surrounding carbon chain replacement method: this method replaces the carbon chain group in the alkoxide ion, alkoxide group or acyloxy ion, acyloxy group while maintaining the center region and the surrounding hydrogen bond network. Because the carbon chain part in the cluster structure extends to the outside, changing its length has little effect on the center region and hydrogen bond network of the cluster, so a series of homologous molecular cluster structures of the same metal but different carbon chain lengths can be obtained while maintaining the basic configuration characteristics of the cluster.

[0066] Example 1: Structure prediction from sodium acetate-acetic acid cluster (C2H3O2Na·(C2H4O2)4) to lithium acetate-acetic acid cluster (C2H3O2Li·(C2H4O2)4), including the following steps:

[0067] Step one, structure determination of sodium acetate-acetic acid cluster

[0068] Firstly, the sodium acetate-acetic acid cluster (C2H3O2Na·(C2H4O2)4) was sampled using the ABCluster package to obtain a large number of possible stable configurations; the top 50 structures with the lowest energy were selected as candidate configurations after preliminary energy ranking; then the density functional theory method was used to further optimize these candidate configurations: first, the structure optimization and vibration frequency calculation were performed at the B3LYP-D3 / 6-311G(d) theoretical level, and finally the electronic energy contribution was calculated at the M06-2X-D3 / 6-311G(d) theoretical level. All the above calculations using the density functional theory were completed by the Gaussian 16 software package. Finally, the structure with the lowest energy was selected as the lowest energy configuration of the sodium acetate-acetic acid cluster (C2H3O2Na·(C2H4O2)4).

[0069] Step two, predicting the structure of lithium acetate-acetic acid cluster by replacing the central metal

[0070] On the basis of maintaining the overall configuration of the cluster and the hydrogen bond network skeleton, the sodium ion in sodium acetate (C2H3O2Na) was replaced by a lithium ion to form the initial structure of the lithium acetate-acetic acid cluster (C2H3O2Li·(C2H4O2)4). Since sodium ions and lithium ions are both alkali metals, they have similar outer electron configurations and chemical properties, and such replacement can maintain the basic structural characteristics of the cluster. Density functional theory calculations were performed on the obtained lithium acetate-acetic acid cluster structure using the same calculation method and theoretical level as in step one.

[0071] Step three, structure verification and comparative analysis

[0072] To verify the reliability of the central metal replacement method, the ABCluster package was used to perform complete configuration sampling on the lithium acetate-acetic acid cluster (C2H3O2Li·(C2H4O2)4), and the most stable configuration was determined by the same density functional theory method. As shown in Figure 4 , the structures of the lithium acetate-acetic acid cluster obtained by the two methods were compared: (1) energy comparison: the structure energies obtained by the two methods were almost completely consistent, with a difference of only 0.17 kJ·mol -1 ; (2) structure parameter comparison: the average bond length difference between the lithium ion and the oxygen atom in C2H3O2 - was only 0.02 Å; (3) hydrogen bond network comparison: the configurations obtained by the two methods both maintained similar hydrogen bond arrangement patterns. The above results show that the central metal replacement method can accurately predict the stable structure of carboxylate molecular clusters with different metal ions in the same main group.

[0073] Example 2: Structure prediction from sodium ethoxide·ethanol cluster (C2H5ONa·(C2H5OH)6) to potassium ethoxide·ethanol cluster (C2H5OK·(C2H5OH)6), including the following steps:

[0074] Step one, structure determination of sodium ethoxide·ethanol cluster

[0075] First, the ABCluster package was used to sample the configurations of sodium ethoxide·ethanol cluster (C2H5ONa·(C2H5OH)6), obtaining a large number of possible stable configurations; the sampled configurations were preliminarily sorted by energy, and the top 50 structures with the lowest energy were selected as candidate configurations; then, density functional theory was used to further optimize these candidate configurations: first, structure optimization and vibration frequency calculation were performed at the B3LYP-D3 / 6-311G(d) theoretical level, and finally electronic energy contribution was calculated at the M06-2X-D3 / 6-311G(d) theoretical level, all of which were completed by the Gaussian 16 software package. Finally, the structure with the lowest energy was selected as the lowest energy configuration of sodium ethoxide·ethanol cluster (C2H5ONa·(C2H5OH)6).

[0076] Step two, predicting the structure of potassium ethoxide·ethanol cluster using central metal replacement method

[0077] On the basis of maintaining the overall configuration of the cluster and the hydrogen bond network skeleton, the sodium ion in sodium ethoxide (C2H5ONa) was replaced with a potassium ion to form the initial structure of potassium ethoxide·ethanol cluster (C2H5OK·(C2H5OH)6). Since sodium ions and potassium ions are both alkali metals, they have similar outer electron configurations and chemical properties, and such replacement can maintain the basic structural characteristics of the cluster. Density functional theory calculations were performed on the obtained potassium ethoxide·ethanol cluster structure using the same calculation method and theoretical level as in Step one.

[0078] Step three, structure verification and comparative analysis

[0079] To verify the reliability of the central metal replacement method, the ABCluster package was used to perform complete configuration sampling on potassium ethoxide·ethanol cluster (C2H5OK·(C2H5OH)6), and its most stable configuration was determined by the same density functional theory method. As shown in Figure 5 , the structures of potassium ethoxide·ethanol cluster obtained by the two methods were compared: (1) energy comparison: the structure energies obtained by the two methods are almost completely consistent, with a difference of only 0.09 kJ·mol -1 ; (2) structure parameter comparison: the potassium ion and C2H5O -(3) hydrogen bond network comparison: both methods obtained similar hydrogen bond arrangement patterns. The above results show that the central metal replacement method can accurately predict the stable structure of alcoholate molecular clusters of different metal ions in the same main group.

[0080] Example 3: Structure prediction from sodium ethoxide-ethanol cluster (C2H5ONa·(C2H5OH)7) to sodium methoxide-methanol cluster (CH3ONa·(CH3OH)7), including the following steps:

[0081] Step one, structure determination of sodium ethoxide-ethanol cluster

[0082] First, the ABCluster program package is used to sample the configurations of the sodium ethoxide-ethanol cluster (C2H5ONa·(C2H5OH)7), obtaining a large number of possible stable configurations; the top 50 structures with the lowest energy are selected as candidate configurations after preliminary energy sorting of the sampled configurations; then the density functional theory method is used to further optimize these candidate configurations: first, structure optimization and vibration frequency calculation are performed at the B3LYP-D3 / 6-311G(d) theoretical level, and finally electronic energy contribution is calculated at the M06-2X-D3 / 6-311G(d) theoretical level. All density functional theory calculations are completed by the Gaussian 16 software package. Finally, the structure with the lowest energy is selected as the lowest energy configuration of the sodium ethoxide-ethanol cluster (C2H5ONa·(C2H5OH)7).

[0083] Step two, prediction of sodium methoxide-methanol cluster structure using surrounding carbon chain replacement method

[0084] Using the RDKit molecular modeling program package, based on the obtained stable sodium ethoxide-ethanol cluster (C2H5ONa·(C2H5OH)7) structure, the following operations are performed: remove the methyl group (-CH3) at the end of the carbon chain in the ethoxy ion (C2H5O - ) and ethoxy group (C2H5O-), and supplement hydrogen atoms at the position where the methyl group is removed, forming the structure of sodium methoxide-methanol cluster (CH3ONa·(CH3OH)7); perform density functional theory calculations on the obtained sodium methoxide-methanol cluster structure, using the same calculation method and theoretical level as in step one.

[0085] Step three, structure verification and comparative analysis

[0086] To verify the reliability of the surrounding carbon chain replacement method, the ABCluster program package is used to perform complete configuration sampling on the sodium methoxide-methanol cluster (CH3ONa·(CH3OH)7), and the most stable configuration is determined by the same density functional theory method. As Figure 6The structures of sodium methoxide methanol clusters obtained by the two methods were compared: (1) energy comparison: the energies of the structures obtained by the two methods were almost completely consistent, with a difference of only 0.25 kJ·mol -1 ; (2) structure parameter comparison: the bond length difference between the sodium ion and the oxygen atom in CH3O - ; (3) hydrogen bond network comparison: the configurations obtained by the two methods both maintained similar hydrogen bond arrangement patterns. The above results show that the surrounding carbon chain replacement method can accurately predict the stable structure of a molecular cluster of the same metal but a shorter carbon chain homolog.

[0087] Example 4: Structure prediction from sodium ethoxide ethanol cluster (C2H5ONa·(C2H5OH)6) to sodium propanol propanol cluster (C3H7ONa·(C3H7OH)6), including the following steps:

[0088] Step one, structure determination of sodium ethoxide ethanol cluster

[0089] First, the ABCluster program package was used to sample the configurations of the sodium ethoxide ethanol cluster (C2H5ONa·(C2H5OH)6), and a large number of possible stable configurations were obtained. The top 50 structures with the lowest energy were selected as candidate configurations after preliminary energy sorting of the sampled configurations. Then, the density functional theory method was used to further optimize these candidate configurations: first, structure optimization and vibration frequency calculation were performed at the B3LYP-D3 / 6-311G(d) theoretical level, and finally, electronic energy contribution was calculated at the M06-2X-D3 / 6-311G(d) theoretical level. All the above density functional theory calculations were completed by the Gaussian 16 software package. Finally, the structure with the lowest energy was selected as the lowest energy configuration of the sodium ethoxide ethanol cluster (C2H5ONa·(C2H5OH)6).

[0090] Step two, prediction of the structure of the sodium propanol propanol cluster by the surrounding carbon chain replacement method

[0091] Using the RDKit molecular modeling program package, based on the obtained stable sodium ethoxide ethanol cluster (C2H5ONa·(C2H5OH)6) structure, the following operations were performed: the ethoxy ion (C2H5O -) and ethoxy (C2H5O-), any one hydrogen atom at the end of the carbon chain is replaced by a methyl group (-CH3), at this time the structure parameters of the carbon chain skeleton of propoxy (C3H7O-) can refer to the characteristic values of the five isomers of propanol monomer molecules, namely the ∠HOCC dihedral angle on the main chain is 0° or ± 60°, the ∠OCCC dihedral angle is ± 60°, and accordingly the initial structure of sodium propanol·propanol cluster (C3H7ONa·(C3H7OH)6) is generated; the structure of the obtained sodium propanol·propanol cluster is subjected to density functional theory calculation, and the same calculation method and theoretical level as step one are adopted.

[0092] Step three, structure verification and comparative analysis

[0093] In order to verify the reliability of the surrounding carbon chain replacement method, the ABCluster program package is used to perform complete configuration sampling on the sodium propanol·propanol cluster (C3H7ONa·(C3H7OH)6), and the most stable configuration thereof is determined by the same density functional theory method. As shown in Figure 7 , the structures of the sodium propanol·propanol cluster obtained by the two methods are compared: (1) energy comparison: the structure energies obtained by the two methods are almost completely consistent, and the difference is only 0.07 kJ·mol -1 ; (2) structure parameter comparison: the bond length difference between the sodium ion and the oxygen atom in C3H7O - is only 0.01 Å; (3) hydrogen bond network comparison: the configurations obtained by the two methods both maintain similar hydrogen bond arrangement modes. The above results show that the surrounding carbon chain replacement method can accurately predict the stable structure of the molecular cluster of the same metal but longer carbon chain homologues.

Claims

1. A method for the generation of similar metal alkoxide or metal carboxylate molecular clusters based on general structural features, characterized by, The method comprises the following steps: Step 1: performing a global search on a potential energy surface of the selected metal alkoxide or metal carboxylate to obtain a preliminary candidate configuration set; Subsequently, the density functional theory method is used to first perform structure optimization on the preliminary candidate configuration set, then perform vibration frequency analysis on the optimized structure, select the equilibrium structure with all real frequencies from the optimized structure, confirm that the equilibrium structure is at an energy minimum point, and perform energy calculation, and finally select the lowest-energy cluster configuration; Step 2: analyzing the obtained lowest-energy cluster configuration, and summarizing the mutual complexation mode of the metal alkoxide molecules and alcohol molecules in the cluster or the mutual complexation mode of the metal carboxylate molecules and carboxylic acid molecules in the cluster; The mutual complexation mode of the metal alkoxide molecules and alcohol molecules in the cluster specifically comprises: The metal alkoxide molecules in the inner layer contain metal ions and alkoxy ions, and the metal ions and alkoxy ions are connected in the form of ionic bonds; The alcohol molecules in the outer layer are arranged around the metal alkoxide molecules in the inner layer through a hydrogen bond network, the alcohol molecules contain alkoxy groups, and the carbon chains of the alkoxy groups extend outward in a direction away from the metal alkoxide molecules; The mutual complexation mode of the metal carboxylate molecules and carboxylic acid molecules in the cluster specifically comprises: The metal carboxylate molecules in the inner layer contain metal ions and acyloxy ions, and the metal ions and acyloxy ions are connected in the form of ionic bonds; The carboxylic acid molecules in the outer layer are arranged around the metal carboxylate molecules in the inner layer through a hydrogen bond network, the carboxylic acid molecules contain acyloxy groups, and the carbon chains of the acyloxy groups extend outward in a direction away from the metal carboxylate molecules; Step 3: according to the mutual complexation mode of the metal alkoxide molecules and alcohol molecules in the cluster, replacing the metal ions with other metal ions in the same main group, or / and replacing the carbon chains of the alkoxy ions and alkoxy groups with C1 to C5 straight carbon chains; According to the mutual complexation mode of the metal carboxylate molecules and carboxylic acid molecules in the cluster, replacing the metal ions with other metal ions in the same main group, or / and replacing the carbon chains of the acyloxy ions and acyloxy groups with C1 to C5 straight carbon chains; Finally, a replaced structure is obtained; Step 4: using the density functional theory method to optimize the replaced structure, then performing vibration frequency analysis on the optimized structure, and finally performing energy calculation to obtain a similar metal alkoxide or metal carboxylate molecular cluster structure.

2. The method of claim 1, wherein, In step 1, the global search adopts the ABCluster global optimization program package.

3. The method of claim 1, wherein, In steps 1 and 3, the Gaussian quantum chemistry calculation program or the ORCA quantum chemistry calculation program is used to first perform structure optimization, then perform vibration frequency analysis on the optimized structure, and finally perform energy calculation.

4. The method of claim 1, wherein, In step 3, the Materials Studio molecular modeling software, the GaussView molecular modeling software, the RDKit molecular modeling program package or the OpenBabel molecular modeling program package is used to replace the metal ions with other metal ions in the same main group.

5. The method of claim 1, wherein, In step three, the alkoxyl ion, the carbon chain in the alkoxyl group is replaced with a straight carbon chain of C1 to C5 or the acyloxyl ion, the carbon chain in the acyloxyl group is replaced with a straight carbon chain of C1 to C5 using RDKit molecular modeling package or OpenBabel molecular modeling package.

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