1、2023-9-91Chemistry Department of Fudan UniversityPhysical ChemistryChapter VI Interaction between Molecules2023-9-92Chemistry Department of Fudan University61 Intermolecular interaction 1873-van der Waals1910 Noble Prize in PhysicsWeak interactions between molecules(18371923)(P+a/V2)(V-b)=RT 2023-9-
2、93Chemistry Department of Fudan University(1)Keesom 1912Dipole-dipole interactions between two polar molecules2226e1202/(4)3EkTR (1876-1956),2023-9-94Chemistry Department of Fudan UniversityDebye 1920-1921A molecule with permanent dipole can induce a dipole of a neighboring polarizability molecule(p
3、olarizability a a).The interaction of the induced dipole with the permanent dipole can be written as:2226p12210()/(4)ERa a 1884-19661936 Noble Prize in Chemistry2023-9-95Chemistry Department of Fudan UniversityFor similar molecules,if a a1=a a2=a a,1=2=,then226p02/4ERa（）2023-9-96Chemistry Department
4、 of Fudan University(3)Dispersion interactionTransient dipole interactions1930-London26d1 2121203/()/42EI IIIRa a（）1900-19542023-9-97Chemistry Department of Fudan University(4)Total Energy of intermolecular interactions22221212 1 2epd12126012231(4)32I IEEEERkTII a aa a（）2023-9-98Chemistry Department
5、 of Fudan UniversityPartition of van der Waals interactionDipole momentPolarizabilitymolecule2023-9-99Chemistry Department of Fudan UniversityBA3AB2BA1ABCCCdpe0B0AEEEEEEThe interaction energy of AB can be obtained using Variational Principle(Quantum mechanics)2023-9-910Chemistry Department of Fudan
6、University(5)Intermolecular potential energyattr6BER repnAER(n=8-16)2023-9-911Chemistry Department of Fudan UniversitymnattrrepRBRAEEE612RBRAEEEattrrepn=6,m=12Lennard-Jones potential energyJohn Edward Lennard-Jones1894-1954 2023-9-912Chemistry Department of Fudan UniversityLennard-Jones potential en
7、ergy curve2023-9-913Chemistry Department of Fudan University126ee2RRERR1264ERRConversion between SLM and GMC5vOh Final Pathway 1 -173.252378 -170.522309 -172.877736 Final Pathway 2 -172.877736 -170.049554 -170.217678 Final Pathway 3 -170.217678 -169.576060 -170.361742 Final Pathway 4 -170.361742 -17
8、0.197572 -170.262953 Final Pathway 5 -170.262953 -170.172264 -170.215483 Final Pathway 6 -170.215482 -170.006935 -170.327349 Final Pathway 7 -170.327349 -169.655903 -173.928427In total 55000 pathwaysIdentify 30 pathways with the lowest barrier3.67 from C5v4.35 from Oh-169.576060-173.252378-173.92842
9、7It can be done!But,huge computer resources icosahedronTruncated octahedronLJ38 cluster2023-9-916Chemistry Department of Fudan UniversityVan der Waals radiusPrimary alkane2023-9-917Chemistry Department of Fudan UniversitynRTpV 62 Intermolecular interactions of gasRTpV mFor ideal gas:2023-9-918Chemis
10、try Department of Fudan University(1)Real gas and van der Waals equationRTpVZmFor ideal gas,Z=12023-9-919Chemistry Department of Fudan UniversityIdeal gas2023-9-920Chemistry Department of Fudan UniversityVirial equation of state3m2mmm1VDVCVBRTpVB,C,D:the second,third and fourth Virial coefficient202
11、3-9-921Chemistry Department of Fudan University100K273K373K600KHe11.412.011.310.4Ne-6.010.412.313.8Ar187.021.74.211.9Kr-62.9-28.71.7Xe-153.7-81.7-19.6H2-2.013.715.6N2-160.0-10.56.221.7O2-197.5-22.0-3.712.9CO2-142-72.2-12.4CH4-53.6-21.28.1Air-167.3-13.53.419.0the second virial coefficient2023-9-922Ch
12、emistry Department of Fudan UniversityRTbVVapm2m22n apVnbnRTVVm=V/nVan der Waals equation:2023-9-923Chemistry Department of Fudan University)molLatm/(22a)molL10/(12b)molLatm/(22a)molL10/(12bHe0.034572.370H2O5.5363.049Ne0.21351.709H2S4.4904.287Ar1.3633.219CO23.6404.267Kr2.3493.978SO26.8035.636Xe4.250
13、5.105NH34.2253.707H20.24762.661CH42.2834.278N21.4083.913C2H44.5305.714O21.3783.183C2H65.5626.380Cl26.5795.622C6H618.2411.54CO1.5053.985Van der Waals constants:2023-9-924Chemistry Department of Fudan University(2)Critical and supercriticalCritical pointCritical pressureCritical volume2023-9-925Chemis
14、try Department of Fudan University(3)Corresponding state lawcrcmrcr;TTTVVVpppReduced variables:2023-9-926Chemistry Department of Fudan Universitymethanenitrogenpropaneethylene2023-9-927Chemistry Department of Fudan University2c2rcrcrcrVVabVVTRTpp02dd3c2ccccVab)(VRTVpAt the critical point,pr,Tr and V
15、r all equal to 12c234cccd260dpRTaV(Vb)V 2023-9-928Chemistry Department of Fudan UniversityRbaTbapV278;27;b3c2cc2r2rr2r9327827Vbab)bVb(aTbap2rrrr3138VVTp2023-9-929Chemistry Department of Fudan University63 Intermolecular interactions in liquid1.The structure of liquid and radial distribution function
16、 J(R)Long range-disorderedShort range-ordered but components vary all the timeThe structure of liquid is the spatial distribution and arrangement of liquid molecules2023-9-930Chemistry Department of Fudan UniversityThe structure of liquid can usually be described by the radial distribution function,
17、J(R)or the pair-correlation function g(R)：2)(4)(RRgRJ/N V-average particle density of liquid J(R)dR is the probability of finding another particle within a spherical shell with radius R and thickness dR defined by the center particle.2023-9-931Chemistry Department of Fudan UniversityTypical radial d
18、istribution curve of simple liquidPeak is close to the minimum of U2(R)wide-shell structureg2(R)0 due to molecular repulsion2023-9-932Chemistry Department of Fudan UniversityThe structure of liquid mainly depends on the density The structure of liquid mainly depends on the density of liquid and is l
19、ess perturbed by temperatureof liquid and is less perturbed by temperatureThe J(R)curves of liquid Ar at different temperatures Ar2023-9-933Chemistry Department of Fudan UniversityThe J(R)curves of liquid Ar at different densitiesAr As the increase of liquid density,the population of short-range ord
20、ered structures also increases2023-9-934Chemistry Department of Fudan University if define the coordination number of liquid(Z)as the number of particles at the first coordination spherical shell,then Z ismm002d)(d)(4RRRRJRRRgZ2023-9-935Chemistry Department of Fudan University2.Measurement and calcu
21、lation of J(R)The radial distribution function can be determined experimentally by X-ray or neutron diffraction220201sin()(1 cos)14()1d2SRIIngRRRSR2sin4SwhereDiffraction intensity can be correlated with diffraction angle:2023-9-936Chemistry Department of Fudan UniversityTheoretical calculation of J(
22、R)N212N4312ddddddeNRRRNRRRRgVVNpotential energyTkB/1Molecular dynamics Monte Carlo simulation2023-9-937Chemistry Department of Fudan University6-4 Supermolecule chemistry and molecular assembly Supermolecule chemistry is concerned with molecular assemblies with special structure and function,consist
23、ing of two or more chemical species glued together through intermolecular interaction.1.Supermolecule2.Supermolecule assemblyseveral components:donor and acceptorsa vast number of componentssuch as films,colloids2023-9-938Chemistry Department of Fudan University Electrostatic Hydrogen bonding Metal-
24、ligand interaction -stacking Induced dipole-induced dipole interaction Hydrophobic effectIntermolecular interactions in supermolecule 2023-9-939Chemistry Department of Fudan UniversityMolecular recognition Supermolecular self-assemblyDonor and acceptor selectivityOrdered structure2023-9-940Chemistry Department of Fudan UniversityCrown ether and cryptandMolecular recognition between crown ether and NH4+2023-9-941Chemistry Department of Fudan UniversityHydrogen bonding recognition and self-assembly
