98837-51-5Relevant articles and documents
Linear and nonlinear optical properties of a quadrupolar carbo-benzene and its benzenic parent: The carbo-merization effect
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
, (2021/01/28)
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.
Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
supporting information, p. 1799 - 1802 (2019/01/25)
Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
Oligothiophene-Bridged Conjugated Covalent Organic Frameworks
Keller, Niklas,Bessinger, Derya,Reuter, Stephan,Calik, Mona,Ascherl, Laura,Hanusch, Fabian C.,Auras, Florian,Bein, Thomas
supporting information, p. 8194 - 8199 (2017/06/27)
Two-dimensional covalent organic frameworks (2D-COFs) are crystalline, porous materials comprising aligned columns of π-stacked building blocks. With a view toward the application of these materials in organic electronics and optoelectronics, the construction of oligothiophene-based COFs would be highly desirable. The realization of such materials, however, has remained a challenge, in particular with respect to laterally conjugated imine-linked COFs. We have developed a new building block design employing an asymmetric modification on an otherwise symmetric backbone that allows us to construct a series of highly crystalline quaterthiophene-derived COFs with tunable electronic properties. Studying the optical response of these materials, we have observed for the first time the formation of a charge transfer state between the COF subunits across the imine bond. We believe that our new building block design provides a general strategy for the construction of well-ordered COFs from various extended building blocks, thus greatly expanding the range of applicable molecules.
