Charge transfer states formation

Fig. 7 (a) Molecular orbital (MO) description for the charge-transfer state formation in organic donor/ acceptor systems, (b) Description for CT state emission energy using exciplex MOs in (a)... 

Kajimoto, O., Futakami, M., Kobayashi, T., and Yamasaki, K., "Charge-Transfer-State Formation in Supercritical Fluid (N,N-Dimethylamino)benzonitrile in CF3H," J. Phys. Chem., 1988, 92, 1347. 

An extremely interesting study is that on charge transfer state formation from (J, N-d ime t h y lamino ) benzon i t r ile in CF3H in... 

King SM, Hintschich SI, Dai D, Rothe C, Monkman AP (2007) Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer. J Phys Chem C 111 18759-18764... 

The electronic structure of interfacial excitations was recently described by Beljonne, Herz, Friend, and coworkers [38,88]. Static dipoles in the ground state of one polymer chain are considered to modulate the exciton energy on the neighboring polymer chains by Coulomb interactions across the heterojunction. Depending on the relative position of the chains, attractive or repulsive interaction were found, which respectively stabilize or obstruct charge-transfer state formation [88]. This implies that the density of states of interfacial excitons is broader than that for bulk excitons. Indeed, this was experimentally observed by femtosecond time-resolved photoluminescence spectroscopy in the same study [88]. The broader density of states at the heterojunction is consistent with the fast directional motion toward the interface described above (see Section 13.3.1) [87]). Excitons could transfer quickly into lower energy interfacial sites when they approach the interfacial region. 

Kajimoto, O., M. Futakami, T. Kobayashi, and K. Yamasaki 1988, Charge-transfer-state formation in supercritcal fluid (N,N-dimethylamino)benzonitrile in CF3H . J. Phys. Chem. 92, 1347. 

O Kajimoto, M Futakami, T Kobayashi, K Yamasaki. Charge-transfer-state formation in supercritical fluid (V,V-dimethylamino)benzonitrile in CF3H. J Phys Chem 92 1347, 1988. 

O Kajimoto, T Nayuki, T Kobayashi. Picosecond dynamics of the twisted intramolecular charge-transfer state formation of 4-(V,A-dimethylarnino)benxonitrile (DMABN) in supercritical fluid solvent. Chem Phys Lett 209 357, 1993. 

The ethylenediamine derivative [31] possesses higher promoting activities than other diamines. This phenomenon may be ascribed to the copromoting effect of the two amino groups on the decomposition of persulfate through a CCT (contact charge transfer complex) formation. So we proposed the initiation mechanism via CCT as the intimate ion pair and deprotonation via CTS (cyclic transition state) as follows ... 

Anthracene has also been used as an acceptor (Fig. 10). In solution, 26 emits a single fluorescence band that is somewhat structured in nonpolar solvents and becomes broad and structureless with increasing polarity [58]. The strongly hindered molecule 27 also exhibits a similar behavior, but its absorption spectrum is better structured [59]. The rate of formation of a charge transfer state is higher for 27 than for 26. Based on this observation, it appears that the twist around the anthryl-phenyl C-C bond plays a significant role in the fluorescence profile of the probes [60]. Acridines, such as 28, behave similarly to anthracene except that acridine is a better electron acceptor [61]. 

Hara K, Bulgarevich DS, Kajimoto O (1996) Pressure tuning of solvent viscosity for the formation of twisted intramolecular charge-transfer state in 4, 4 -diaminophenyl sulfone in alcohol solution. J Chem Phys 104(23) 9431-9436... 

This chapter is restricted to intermolecular photophysical processes2). Intramolecular excited-state processes will not be considered here, but it should be noted that they can also affect the fluorescence characteristics intramolecular charge transfer, internal rotation (e.g. formation of twisted charge transfer states), intramolecular proton transfer, etc. 

The Ea for the dissolution of hematite by mercapto carboxylic acids in acid media in the presence of UV radiation was lower (64 5 kj mol ) than that for dissolution in the absence of radiation (94 8 kJ mol ) (Waite et al. 1986). The reaction in both cases was considered to involve formation of an intermediate organic-Fe surface complex which decomposed as a result of intramolecular electron transfer to release Fe". UV irradiation enhanced the decomposition of the surface complex either through excitation of the ligand field states associated with the free electrons on the S atoms, or through high energy charge transfer states. 

There is no evidence for ground state charge-transfer complex formation between stilbenes and neutral amines. Amine cations and dications are powerful electron acceptors and can form ground state complexes in which t-1 serves as the electron donor. Complex formation between t-1 and the organic dication methyl viologen is responsible for quenching of the fluorescence of surfactant stilbenes in organized assemblies (112). 

Because of the spectral relaxation due to the appearance of a high dipole moment in the charge-transfer state, the dynamics of the TICT state formation has been studied by following the fluorescence rise in the whole A band. In Fig. 5.6 are plotted, in the 10 ns time range, the experimental curve iA(t) at -110°C in propanol (tj = 1.5 x 103 cp) and the decay of the B emission at 350 nm. The solid curve representing the evolution of the TICT state expected in a constant reaction rate scheme shows a slower risetime with respect to that of the recorded A emission. To interpret the experimental iA(t) curves, the time dependence of the reaction rate kliA(t) should be taken into account. From the coupled differential equations for the populations nB(t) and nA(t) of the B and A states (remembering that the reverse reaction B <—A is negligible at low temperatures) ... 

Figure 31 Proposed mechanism of the formation of unsaturated carbonyl compounds from the alkene-02 charge-transfer state.

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