The noncoincidence phenomenon of acetonylacetone CO stretching in a binary mixture and the aggregation-induced split theory

Abstract

Both the isotropic and anisotropic Raman wavenumbers of the CO stretch increase with the dilution of acetonylacetone by CCl4, while the separation between isotropic and anisotropic Raman wavenumbers (Δυ) decrease.

The intermolecular interaction and polar bonds aggregation induced spectral splitting phenomenon for binary mixture

“…= ν IR -ν Raman > 0 . The AIS theory can give good explanation for the noncoincidence effect and concentration effect [15][16][17][18] . When the dimer is gradually depolymerized by the dilution process, the internal energy increases and the vibration frequencies of ν [?]…”

“…However, when there are hydrogen bonds in the mixture, the theoretical model fails, and the function shows abrupt change or extreme value 12 . After systematically studying the polarization Raman spectra of a series of binary mixtures of polar molecules such as ethylene trithiocarbonate 13 , acetone 14 and methanol 15 , the theory of aggregation induced spectral splitting (AIS) have been proposed [14][15][16][17][18] . AIS believes that when there is no hydrogen bond or other stronger intermolecular interaction in the system, dipoles ( ) will spontaneously aggregate to form antiparallel arranged dimers ( ) in solution due to dipoledipole interaction, resulting in a significant reduction in dipole moment and internal energy (see Table 1).…”

The intermolecular polar bond interaction and coupling induced spectral splitting phenomenon for a binary mixture

“…12 After systematically studying the polarization Raman spectra of a series of binary mixtures of polar molecules such as ethylene trithiocarbonate, 13 acetone 14 and methanol, 15 the theory of aggregation induced spectral splitting (AIS) has been proposed. [14][15][16][17][18] According to AIS, when there is no hydrogen bond or other stronger intermolecular interactions in a system, dipoles (…”

“…The AIS theory can give good explanation for the noncoincidence effect and concentration effect. [15][16][17][18] When a dimer is gradually depolymerized by the dilution process, the internal energy increases and the vibration frequencies of n 8 and n > increase as well. When a dimer is completely depolymerized into free monomers, n 8 and n > are coincident in the n mono position.…”

“…12 After systematically studying the polarization Raman spectra of a series of binary mixtures of polar molecules such as ethylene trithiocarbonate, 13 acetone 14 and methanol, 15 the theory of aggregation induced spectral splitting (AIS) has been proposed. 14–18 According to AIS, when there is no hydrogen bond or other stronger intermolecular interactions in a system, dipoles () will spontaneously aggregate to form antiparallelly arranged dimers () in solution due to dipole–dipole interactions, resulting in a significant reduction in the dipole moment and internal energy (see Table 1). The dimers tend to be more stable.…”