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From Molecule to Bulk Material: Optical Properties of Hydrogen‐Bonded Dimers [C 12 H 12 N 4 O 2 AgPF 6 ] 2 and [C 28 H 28 N 6 O 3 AgPF 6 ] 2 Depend on the Arrangement of the Oxime Moieties
Author(s) -
Cheng WenDan,
Wu DongSheng,
Shen Juan,
Huang ShuPing,
Xie Zhi,
Zhang Hao,
Gong YaJing
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601190
Subject(s) - dimer , chemistry , delocalized electron , molecule , absorption (acoustics) , crystallography , absorption spectroscopy , pyridine n oxide , pyridine , materials science , physics , organic chemistry , composite material , medicinal chemistry , quantum mechanics
The dependence of the optical properties of [C 12 H 12 N 4 O 2 AgPF 6 ] 2 (dimer‐1) and [C 28 H 28 N 6 O 3 AgPF 6 ] 2 (dimer‐2) on the arrangement of the oxime moieties in the molecule and in bulk crystals was investigated by means of time‐dependent density functional theory. Dimer‐1 with simple pyridine oxime ligands and a wavy arrangement has a smaller dipole moment and larger transition energy between the two states, and thus smaller third‐order polarizabilities and two‐photon absorption cross sections. Dimer‐2 with extended pyridine oxime ligands and a ladder arrangement has a larger dipole moment and smaller transition energy between the two states, and thus larger third‐order polarizabilities and two‐photon absorption cross sections. The lowest energy absorption band is red‐shifted for dimer‐2 as compared with dimer‐1, due to more pronounced π–π delocalization interactions and weaker hydrogen bonding in dimer‐2. The electronic absorption spectra, frequency‐dependent third‐order polarizabilities, and two‐photon absorption cross sections involve significant contributions from charge transfers from π/π* orbitals of the pyridine oxime ligands but no contribution from PF 6 − ions or H 2 O molecules in the wavelength range studied for the monomers and dimers of the C 12 H 12 N 4 O 2 AgPF 6 and C 28 H 28 N 6 O 3 AgPF 6 molecules. The third‐order susceptibilities and two‐photon absorption coefficients of bulk solids were estimated on the basis of the optical properties of the corresponding dimers, and the bulk material constructed from dimer‐2 has the larger optical parameters of the two.