- Linear and nonlinear optical properties of a quadrupolar carbo-benzene and its benzenic parent: The carbo-merization effect
-
Herein, the optical properties of thiophene-functionalized quadrupolar carbo-benzenes and a benzenic parent, of generic structure Th–C[tbnd]C–[core]–C[tbnd]C–Th, Th = R2C4HS, are comparatively investigated. Beyond the previously unknown dioctylthienylethynylbenzene (core = p-C6H4, R = nOct), two bis-dialkylthienylethynyl-carbo-benzenes (core = C18Ph4, R = nOct, nBu) are envisaged for the unique “carbo-aromatic” character of the C18 macrocycle. The three targets were synthesized from the corresponding ethynylthiophenes in 47, 20 and 10% yield, respectively, then characterized by classical methods such as NMR spectroscopy, and X-ray crystallography for one of the carbo-benzenes. Regarding linear and nonlinear optical properties, our results show that the carbo-merization induces a significant shift to lower energies of the one-photon electronic excitations accompanied by an 8-fold increase of the molar extinction coefficient compared to the parent molecule. Intriguingly, these excitations lead to a broad band of photoluminescence comprising decay transitions of the type S1 → S0 but also of the type S2 → S0. This phenomenon of emission from higher excited states, which is contrary to Kasha's rule, is assigned to - or revealed by - a reduction of the internal conversion efficiency between S2 and S1. Two-photon induced transitions are also enhanced, the two-photon absorption cross-section (σ2PA) being in average five times larger for the carbo-benzenes than for their benzene parent in the wavelength range 650–950 nm, with a maximum of σ2PA = 1430 GM (1 GM = 10?50 cm4 s/photon). Beyond a moderate nonlinearity, this comparative study provides quantitative insights about the way carbo-merization or insertion of a π-conjugated macrocycle between chromophoric functions (here thiophene rings) can tune optical properties of organic molecules. The optical properties of the bis-dialkylthienylethynyl-carbo-benzenes are also discussed in regard of recent reports on organic chromophores based on other types of π-conjugated macrocyclic cores.
- Barba-Barba, Rodrigo M.,Chammam, Marwa,Ramos-Ortiz, Gabriel,Listunov, Dymytrii,Velusamy, Jayaramakrishnan,Rodriguez, Mario,Carriles, Ramon,Silva, Carlos,Duhayon, Carine,Kauffmann, Brice,Maraval, Valérie,Chauvin, Remi
-
-
- NOVEL REACTION FOR THE PREPARATION OF ALKYL VINYL SULFIDES USING METAL COMPLEX CATALYSTS
-
The feasibility of the one-step synthesis of mixtures of Z- and E-alkenyl alkyl sulfides via the reaction of elemental sulfur with terminal and disubstituted alkynes and alkyl halides has been demonstrated in the presence of low-valent Ni, Co, Pd, and Fe complexes.The effects of structure in the starting alkynes and alkyl halides have been investigated, along with process conditions and their effect on the composition and yields of reaction products.
- Dzhemilev, U. M.,Baibulatova, N. Z.,Kunakova, R. V.,Tkachenko, T. K.,Tolstikov, G. A.
-
p. 1854 - 1861
(2007/10/02)
-