Structural chemistry is a branch of chemistry that studies the relationship between the configuration and composition of substances at the atomic to molecular level, as well as the interaction between structure and various movements.
It also explains the materialMicrostructureRelating to its macro performanceBasic discipline。Structural chemistry is closely related not only to other chemical disciplines, but also to biological science, geological sciencematerial science andMedicineAnd other disciplines are interrelated, coordinated and mutually promoted.
Due to the establishment of many chemical databases related to material structure, structural chemistry has been increasingly recognized by agronomists andChemical engineerTo which we attach great importance.
Structural chemistry is a direct application of many modernExperimental meansDetermination of molecular static and dynamic structure and staticDynamic performanceOfExperimental science。It is necessary to summarize the material structure from the molecular configuration and motion characteristics of various known chemical substancesRegularityWe should also theoretically explain why atoms combine into molecules, why atoms combine into a large number of molecules in a certain amount, and why atoms combine with each other in moleculesForceMode and relative position of atoms in moleculesStereochemistryfeatures.Structural chemistry also shows that the atoms or groups of certain elements are in different microscopicChemical environmentInValence state、Electronic configurationCoordination characteristicsIsostructurefeatures.
On the other hand, from the perspective of structural chemistry, it can also clarify various macroscopic aspects of substancesChemical properties(including chemical reaction performance) and various macro non chemical properties (including various physical properties andTechnical performanceAnd microstructure.On this basis, it is possible to constantly use the known laws to try to synthesize more novel, more unusual structural featuresNew substances, onChemical bond theoryIn the process of combining with experimental chemistry, new structural chemistry theory is created.At the same time, we should constantly strive to establish new physical and chemical experimental methods to clarify the microstructure of matter.
Like other branches of chemistry, structural chemistry generally recognizes objective chemical substances at different levels from macro to micro, from static to dynamic, from qualitative to quantitative.Deduction and induction are still the basis of structural chemistry researchThinking method。EarlyRelated substancesChemical structureIt can be said that the knowledge ofElement compositionandchemical propertyResearch.At that time, people could only understand chemical substances (including various simple substances and a few compounds) from the laws of material composition, such asConstant ratio law、Multiple ratio lawAnd so on.With the chemical reactionequivalentIt is proposed that“Valence”And used to explain the law of material composition.At that time, we knew nothing about the cause of formation of atomized synthetic molecules and the arrangement of atoms in molecules.
Structural chemistry
The generation of structural chemistry andorganic compoundThe study of molecular composition is closely related.Organic chemistryAt the early stage of development, people concluded thatcarbon atompresenttetrahedronValenceThe law of.In order to explain the diversity of organic composition, it is proposed thatCarbon chainStructure and bond saturation theory of carbon chain.Subsequent organicsIsomerism, Organicfunctional groupStructure andOptical isomerismPhenomenon and other studies also provide strong experimental evidence for early structural chemistry research, prompting chemists to understand the chemical composition andchemical property, and summarize someRelated substancesThe regularity of chemical structure has laid the foundation for the emergence of modern structural chemistry.
The development and application of modern experimental physics methods provide various experimental methods for structural chemistry to determine the microstructure of substances;quantum mechanicsThe establishment and application of the theory can also describe the electronic andNucleusmotion state It provides a theoretical basis.ofatomic structureEspecially in atomsElectron shellAnd the theory that internal and external forces cause movement changes, which establishes the theory thatInteraction forceThe essence of chemical bond is theoretically clarified, which makes peopleIonic bond、covalent bondandCoordination bondDeepen understanding.ofHybrid orbitThe concept of "C" also makes reasonable explanation and even prediction for the spatial configuration of many compounds.In atomsElectronic orbitSpatial orientationIs also characterized byConjugate system(e.gbenzene ring、butadieneAnd their special chemical properties.
theoretical basis
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quantum chemistryIt is the main theoretical basis of modern structural chemistry.In quantum chemistryValence bond theory、Molecular orbital theoryas well asCoordination field theoryIt can be used not only to clarify the characteristics of the molecular composition and the spatial arrangement of atoms, but also to clarify the relationship between microstructure and macro performance.becauseQuantum chemical calculation methodWith the development and gradual improvement of, and the application of high-speed electronic computers, quantum chemical methods related to molecules and their different aggregation states have been possible to be used for the exploration of "molecular design" and preparation methods of special materials, pushing the theory of structural chemistry to a new height.
Discipline progress
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Structural chemistry has become a discipline closely related not only to other chemical disciplines, but also to biological science, geological sciencematerial science And other disciplines are interrelated, coordinated and mutually promoted.Due to the establishment of many chemical databases related to material structure, structural chemistry has been paid more and more attention by agronomists and chemical engineers.
Structural chemistry research mainly includes the following aspects:
1. Structural chemistry of compounds with new configurations, especially cluster structural chemistry andOrganometallic compoundThe research of structural chemistry is active.This type of research involves "chemical modelingBiological nitrogen fixation”And other extremely important topics in theoretical research, as well as application research topics closely related to industrial and agricultural production, such as finding new and efficient industrial catalysts.staynatural productIn the structural chemistry study of,Natural medicine, especially those with anti-cancer activityActive ingredientOur research may also serve as a uniform for human beingscancerMake important contributions.proteinOfspace structureIt is still a difficult and important topic of theoretical significance and practical application value to study the theory of the ".".
2、rare earth elementStructural chemistry of rare earth elements and rich rare earth elements in chinaComprehensive utilization of resourcesIs very close.In theory, it is linked to the orbit of 4f electronFunctional correlation。The relevant research is of great significance to the development of China's rare earth industry.
3、surface structure And surfacechemical reactionResearch andindustrial production Heterogeneous catalytic reactions are closely related, and relevant research is very important for industrial catalysts, especiallysynthetic ammoniaFor industrial productionNew catalystThe research and development of this system has the function of theoretical guidance.
4、Laser spectroscopyandLaser chemistryFor fast dynamic structure and fast chemical reaction dynamic processresearch methodThe establishment of structural chemistry has a far-reaching impact and may lead to the establishment of new means of structural chemistry research.Laser inducedChemical reaction processMore unique.
5. Information engineering research of structural chemistry can make full use of electroniccomputerWith high speed and efficiency, giving full play to the role of structural chemistry databaseSemiempirical theoryAnd the new theory of structural chemistry will have a significant impact.The establishment of relevant methods will play an important role in the realization of "molecular design".
Determination method
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Modern measuring substancesMicrostructureThe establishment of the experimental physical method of the structural chemistry has played a decisive role in promoting the development of structural chemistry.X-rayDiffraction method and principle are quite similarNeutron diffraction、electron diffractionThe discovery and development of such methods have greatly enriched people's understanding of the spatial arrangement of atoms in material molecules (especially molecules in crystals), and provided hundreds of thousands of crystals andmolecular structureReliable structural data.Based on the diffraction measurement of single substances and simple inorganic salts (including minerals) crystals, people have summarized and refined the relevant atoms andIonic radiusData of.For more complex compoundscrystal, also passedDiffraction methodMeasuredKey length、Bond angleetc.Basic parametersWe also found thatBondingDiversity of modes and in different aggregation statesIntermolecular forceDiversity of methods, especially the use of X-rayCrystal diffractionMethods The proteins in nearly 300 kinds of organisms were determinedmacromoleculeThe molecular weight of some proteins reaches hundreds of thousands or even hundreds of thousandsAtomic weightCompany.In addition, through the study of crystal diffraction, people cancrystal structureFrom the angle ofCrystalline stateLowerphysical property(such as optical properties and electrical properties).
Another type of method for determining structure is spectroscopic method.Spectral methods play an important role in providing information about molecular energy levels and motions, especially more detailed and dynamic structural information.Such as molecular vibration spectrum (infrared andRaman spectrum）Is identificationmaterialA quick and powerful tool for the formation of molecular groups.Therefore, it is called the "fingerprint" of chemical substances. Combined with the high-speed information processing function of electronic computers, people can quickly identify the molecular structure of unknown samples through computer retrieval and identification.The theoretical processing of infrared Raman spectrum can also provide information about vibrationForce constantEtcChemical bondSome data of characteristics.Other spectroscopic methods include:Nuclear magnetic resonance spectrum, paramagnetic resonance spectrumElectron spectroscopy(includingPhotoelectron spectroscopy, X-ray photoelectron spectroscopyAuger electron spectroscopy）Mass spectrum (seeMass spectrometry）、Mossbauer spectroscopy, visible-Ultraviolet spectrum、Ord 、Circular dichroismSpectrum (see circular dichroism) andExtended X-ray absorption fine structureEtc.
