“…Interestingly, bridging a certain bond in a polymethinic or polyenic molecule does not always lead to enhancement of the fluorescence quantum yield, as would be expected from the loose bolt theory. ,, Anti-loose-bolt behavior, i.e., a reduced fluorescence quantum yield for the bridged derivative, has been observed in some cyanines (e.g., in 224 ) as well as in donor−acceptor stilbene 225 , in conjunction with multiple fluorescence in the polyene series 225 − 227 . ,,− …”
“…Interestingly, bridging a certain bond in a polymethinic or polyenic molecule does not always lead to enhancement of the fluorescence quantum yield, as would be expected from the loose bolt theory. ,, Anti-loose-bolt behavior, i.e., a reduced fluorescence quantum yield for the bridged derivative, has been observed in some cyanines (e.g., in 224 ) as well as in donor−acceptor stilbene 225 , in conjunction with multiple fluorescence in the polyene series 225 − 227 . ,,− …”
“…The aldehyde series 33 a, 34 a, and 35 a with the corresponding donor groups D acted as the central series and were constructed by means of the Wittig reaction with the extension reagent 36. [46, 58b, 59] Compounds analogous to 38 b-40 b, but with a CN group instead of the NO 2 group, were investigated in the context of their dual fluorescence and twisted intramolecular charge transfer (TICT) states; [60][61][62][63][64][65][66] however, a discussion of these states is beyond the scope of the present Review. [57] The maxima of the long-wavelength absorptions of a selection of compounds 33-35 are listed in Table 3.…”
Conjugated oligomers represent a prominent class of compounds from a viewpoint of their theory, synthesis, and applications in materials science. Push-pull substitution with an electron donor D at one end of the conjugation and an electron acceptor A at the other end results in them having outstanding optical and electronical properties. This Review highlights fundamental synthetic strategies for the preparation of such oligomers with n repeat units (n=1, 2, 3, 4, ..) and the rules that govern their linear and nonlinear optical properties (absorption, frequency doubling and tripling). The unification of chemical, physical, and theoretical aspects with an interdisciplinary image of this class of compounds is attempted herein.
“…[8][9][10][11][12] Thus, donor-acceptor diphenylbutadienes have been found to exhibit solvatochromic behavior attributable to intramolecular charge transfer and TICT state. Further, solvatochromic behavior of diphenylpolyenes in homogeneous and microheterogeneous media have been evaluated, and using photophysics of dipolar ethenes and dienes, attempts have been made to characterize the microenvironment of micelles and vesicles.…”
cyano-1-p-nitrophenyl-4-phenylbuta-1Z,3E-diene (6), and 1-cyano-1-phenyl-4-pnitrophenylbuta-1Z,3E-diene (7), have been synthesized and their absorption and fluorescence properties in organic solvents, water-dioxane, and SDS, CTAB, and Triton-X-100 micelles have been investigated. The fluorescence behavior of these dienes has also been examined in ethanol-methanol (1:1) matrix at 298 and 77 K. The dienes with nitro substituents on the aromatic ring are capable of exhibiting dramatically redshifted fluorescence emission due to twisted intramolecular charge-transfer excited states. The fluorescence properties of nitro-substituted dienes 3, and 5-7 have been utilized to probe the microenvironment of SDS and CTAB micelles in terms of dielectric constant of water-micelle interface, location of the probe molecules in the micelles, and the cmc values. This study has brought out interesting features of the excited state structure and potential energy surface of diphenylpolyenes. It further provides new directions for the development of fluorescence probes as sensors and reporters of microenvironments of organized assemblies.
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