RESUMO
A class of wedge-shaped organic π-fluorophores featuring a 6,9-diphenyl-substituted phenanthroimidazole (PI) core was designed, synthesized, and characterized. Among them, a π-extended PI derivative containing two electron-withdrawing aldehyde groups was found to exhibit versatile solid-state packing properties as well as strong solvatofluorochromism in different organic solvents. Another PI derivative that was functionalized with two electron-donating 1,4-dithiafulvenyl (DTF) end groups showed versatile redox reactivities and quenched fluorescence. Treatment of this wedge-shaped bis(DTF)-PI compound with iodine resulted in oxidative coupling reactions, leading to the formation of intriguing macrocyclic products that carry redox-active tetrathiafulvalene vinylogue (TTFV) moieties in their structures. Mixing the bis(DTF)-PI derivative with fullerene (C60 or C70) in an organic solvent resulted in substantial fluorescence enhancement (turn-on). In this process, fullerene acted as a photosensitizer to generate singlet oxygen, which in turn induced oxidative C = C bond cleavages and converted nonfluorescent bis(DTF)-PI into highly fluorescent dialdehyde-substituted PI. Treatment of TTFV-PI macrocycles with a small amount of fullerene also led to a moderate degree of fluorescence enhancement, but this is not because of photosensitized oxidative cleavage reactions. Instead, competitive photoinduced electron transfer from TTFV to fullerene can be attributed to their fluorescence turn-on behavior.
RESUMO
A series of saddle-shaped donor-acceptor π-systems, termed TTFAQ-AQs, were designed and synthesized. The molecular structures of TTFAQ-AQs feature a π-fused framework containing an anthraquinodimethane extended tetrathiafulvalene (TTFAQ) as the donor and an anthraquinone (AQ) unit as the acceptor. As such, TTFAQ-AQs show enhanced intramolecular charge-transfer properties, which result in amphoteric redox behavior and narrow electronic energy band gaps. Detailed structural and electronic properties were investigated by UV-vis absorption, cyclic voltammetric, and single-crystal X-ray diffraction (SCXRD) analyses. The supramolecular interactions of TTFAQ-AQs with C60 and C70 fullerenes were examined in both the solution and solid phases. Our results showed that the benzoannulated TTFAQ-AQ derivative favors interaction with C70 fullerene through complementary concave-convex interactions. Detailed energetics involved in the TTFAQ-AQ/C70 interactions were assessed by means of density functional theory (DFT) calculations.
RESUMO
A series of 1,3,6,8-tetraphenylpyrene (TPPy) derivatives substituted with redox-active 1,4-dithiafulvenyl (DTF) groups was synthesized and characterized. The conformational properties of these DTF-TPPys and their TPPy precursors were assessed by X-ray single-crystal and nuclear magnetic resonance analyses. Their electronic and redox properties were examined by ultraviolet-visible absorption, fluorescence, and cyclic voltammetric analyses. The DTF substitution was found to strongly modify the absorption, emission, and electrochemical properties, while detailed effects can be linked to substitution patterns and alkyl side chains attached to the DTF groups. Furthermore, the DTF-TPPy derivatives showed sensitivity to acids; in particular, the vinylic proton of DTF group could undergo efficient proton/deuterium exchange with D2O in an acidic medium.
Assuntos
Prótons , Espectroscopia de Ressonância Magnética , Conformação Molecular , OxirreduçãoRESUMO
Three-dimensional covalent connectors are valuable synthons for accessing crystalline or amorphous networks. Currently, fused polycyclic alkanes are employed as connectors in this context. We debut phosphorus-nitrogen (PN) cages as new 3-dimensional (3-D) inorganic connectors that yield crystalline and amorphous networks, including examples with gas porosity. We show that the high tunability of PN cages accelerates network diversification and the presence of a responsive 31P NMR spectroscopic handle provides structural insight. Collectively, this work unlocks a new and convenient 3-D synthon for reticular chemistry.
RESUMO
The absorption and emission properties of various diphenyl-dibenzofulvene (DP-DBF) derivatives were investigated, and their crystallization-induced emission enhancement (CIEE) performances were found to show a clear correlation with the twist angle around the C[double bond, length as m-dash]C bond of the DP-DBF structure.