Journal of Physical Chemistry A published new progress about 57103-14-7. 57103-14-7 belongs to isoxazole, auxiliary class Fused Tricycles,Carbazoles, name is 9-(4-Fluorophenyl)-9H-carbazole, and the molecular formula is C18H12FN, COA of Formula: C18H12FN.
Galievsky, Victor A. published the artcileUltrafast intramolecular charge transfer with N-(4-Cyanophenyl)carbazole. Evidence for a LE precursor and dual LE + ICT fluorescence, COA of Formula: C18H12FN, the publication is Journal of Physical Chemistry A (2010), 114(48), 12622-12638, database is CAplus and MEDLINE.
The photophysics of N-(4-cyanophenyl)carbazole (NP4CN) was investigated by using absorption and fluorescence spectra, picosecond fluorescence decays, and femtosecond transient absorption. In the nonpolar n-hexane as well as in the polar solvent acetonitrile (MeCN), a locally excited (LE) state is detected, as a precursor for the intramol. charge transfer (ICT) state. A LE â?ICT reaction time Ï2 at 22 °C of 0.95 ps in Et cyanide (EtCN) and 0.32 ps in MeCN is determined from the decay of the LE excited state absorption (ESA) maximum around 620 nm. In the ESA spectrum of NP4CN in n-hexane at a pump-probe delay time of 100 ps, an important contribution of the LE band remains alongside the ICT band, in contrast to what is observed in EtCN and MeCN. This shows that a LE â?ICT equilibrium is established in this solvent and the ICT reaction time of 0.5 ps is equal to the reciprocal of the sum of the forward and backward ICT rate constants 1/(ka + kd). In the photostationary S0 â?Sn absorption spectrum of NP4CN in n-hexane and MeCN, an addnl. CT absorption band appears, absent in the sum of the spectra of its electron donor (D) and acceptor (A) subgroups carbazole and benzonitrile. This CT band is located at an energy of â?000 cm-1 lower than for N-phenylcarbazole (NPC), due to the larger electron affinity of the benzonitrile moiety of NP4CN than the Ph subunit of NPC. The fluorescence spectrum of NP4CN in n-hexane at 25 °C mainly consists of a structured LE emission, with a small ICT admixture, indicating that a LE â?ICT reaction just starts to occur under these conditions. In di-n-pentyl ether (DPeE) and di-Bu ether (DBE), a LE emission is found upon cooling at the high-energy edge of the ICT fluorescence band, caused by the onset of dielec. solvent relaxation. This is not the case in more polar solvents, such as di-Et ether (DEE) and MeCN, in which a structureless ICT emission band fully overlaps the strongly quenched LE fluorescence. For the series of D/A mols. NPC, N-(4-fluorophenyl)carbazole (NP4F), N-[4-(trifluoromethyl)phenyl]carbazole (NP4CF), and NP4CN, with increasing electron affinity of their Ph subgroup, an ICT emission in n-hexane 25°C only is present for NP4CN, whereas in MeCN an ICT fluorescence is observed with NP4CF and NP4CN. The ICT fluorescence appears when for the energies E(ICT) of the ICT state and E(S1) of the lowest excited singlet state the condition E(ICT) â?E(S1) holds. E(ICT) is calculated from the difference E(D/D+) – E(A–/A) of the redox potentials of the D and A subgroups of the N-phenylcarbazoles. From solvatochromic measurements with NP4CN an ICT dipole moment μe(ICT) = 19 D is obtained, somewhat larger than the literature values of 10-16 D, because of a different Onsager radius Ï. The carbazole/phenyl twist angle θ = 45° of NP4CN in the S0 ground state, determined from X-ray crystal anal., has become smaller for its ICT state, in analogy with similar conclusions for related N-phenylcarbazoles and other D/A mols. in the literature.
Journal of Physical Chemistry A published new progress about 57103-14-7. 57103-14-7 belongs to isoxazole, auxiliary class Fused Tricycles,Carbazoles, name is 9-(4-Fluorophenyl)-9H-carbazole, and the molecular formula is C18H12FN, COA of Formula: C18H12FN.
Referemce:
https://en.wikipedia.org/wiki/Isoxazole,
Isoxazole | C3H3NO – PubChem