共查询到4条相似文献,搜索用时 15 毫秒
1.
Umadevi M Vanelle P Terme T Rajkumar BJ Ramakrishnan V 《Journal of fluorescence》2008,18(6):1139-1149
Solvatochromic and preferential solvation of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone (DHDMAQ) have been investigated
using optical absorption and fluorescence emission techniques. Optical absorption spectra of DHDMAQ in different solvents
show the intra molecular charge transfer band in the region 400–550nm. The observed blue shift with solvent polarity indicates
the delocalisation of the excited state, owing to reduction in quasiaromaticity of the chelate rings formed by intra molecular
hydrogen bonds, due to electrostatic or hydrogen bonding interaction. This is also confirmed by the observed low oscillator
strength and the transition dipole moment. The observed quantum yield of DHDMAQ in different solvents is due to the inter
molecular hydrogen bond in the excited state in addition to the intra molecular hydrogen bond. It also reveals from the low
oscillator strength, which indicates that the radiative decay is low. Excited state dipole moment of DHDMAQ is calculated
by solvatochromic data
and it shows a lower value than ground state dipole moment. The preferential solvation parameter shows that in dimethyl formamide
(DMF) + ethanol mixture, the DHDMAQ is preferentially solvated by ethanol in DMF rich region and by DMF in ethanol rich region.
In the case of DMF + dichloromethane mixture DHDMAQ is preferentially solvated by DMF. 相似文献
2.
Size effect of silver nano particles on the photophysical properties of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone (DHDMAQ)
have been investigated using optical absorption and fluorescence emission techniques. Silver nanoparticles of different sizes
have been prepared by Creighton method using magnetic stirrer and ultrasonic field. Quenching of fluorescence of DHDMAQ has
been found to increase with decrease in the size of the silver nanoparticles. Stern–Volmer quenching constants have also been
calculated. 相似文献
3.
Sasirekha V Vanelle P Terme T Meenakshi C Umadevi M Ramakrishnan V 《Journal of fluorescence》2007,17(5):528-539
Optical absorption and fluorescence emission spectra of 2,3-bis(chloromethyl)-1,4-anthraquinone (DCMAQ) in single solvents
namely, carbon tetrachloride, acetonitrile, chloroform, propan-2-ol and its binary mixtures [carbon tetrachloride/chloroform,
chloroform/acetonitrile, chloroform/propan-2-ol] have been investigated. The preferential solvation of DCMAQ in above mixtures
has been studied by monitoring the absorption and fluorescence spectra of DCMAQ. The spectral features indicate that DCMAQ
is preferentially solvated by CHCl3 in the above mixtures. This can be elucidated from the local mole fraction, non-linearity in transition energy plot, preferential
solvation index (δ
s2) and (f
2/f
1) values. Molecular recognition properties of p-tert-butylcalix[4]arene (tBC) to DCMAQ via hydrogen bonding and π–π interaction were sensed successfully on the basis of
absorption and fluorescence emission spectroscopies, by which the stoichiometry ratio and the binding constant of the tBC–DCMAQ
complex were determined. 相似文献
4.
Solvent effects on 2,3-bis(chloromethyl)-1,4-anthraquinone (DCMAQ) and the molecular recognition of DCMAQ in calix[8]arene were investigated using optical absorption and fluorescence emission techniques. Optical absorption spectra show n→π* band in 350–500 nm region. It also indicates that the dipole–dipole interaction and solvent reorganization energies are responsible for the observed features in different solvents. The observed quantum yield of DCMAQ in different solvents is due to the formation of intermolecular hydrogen bond and reorientation of solvent molecule in the excited state of DCMAQ. Excited state dipole moment of DCMAQ is calculated by solvatochromic data and it shows a higher excited state dipole moment than ground state dipole moment. Optical absorption and fluorescence studies of DCMAQ in calix[8]arene elucidate the evidence for the formation of complex between DCMAQ and calix[8]arene. The inclusion ratios and inclusion constant of the host–guest complexes are also determined. 相似文献