ABSTRACT
Herein, we report the synthesis of anthracene-containing twisted cyclo[2]dipyrrin 1 by utilizing a non-planar building block, 1,5-dipyrrylanthracene (1,5-DPA). The non-planar nature of the macrocycle enhanced the solubility and helped in structural characterization. Macrocycle 1 adopts a twisted 'figure of eight' conformation stabilized by strong intramolecular H-bonding interactions and exists as a pair of helical enantiomers, as revealed by X-ray crystallographic analysis. More importantly, the sterically locked structure enabled facile optical resolution using chiral HPLC. The (P,P) and (M,M) enantiomers show moderate chiroptical properties, such as absorption dissymmetry factors |gabs | in the order of 10-3 , and luminescence dissymmetry factors |glum | of 3.8×10-3 and 2.9×10-3 at 702â nm, respectively.
ABSTRACT
The introduction of a pyrrole ring at one of the meso positions of carbazole-based porphyrins lowers the structural symmetry and results in dual emission, which strongly depends on the excitation wavelength and temperature. The origin of dual emission induced by NH-tautomerism is confirmed via photophysical and DFT calculations.
ABSTRACT
The synthesis of a new class of carbazole based macrocycles via [3 + 1] acid-catalyzed condensation is reported. Spectroscopic investigations and computational studies imply that these macrocycles have a large influence on the electronic structure in comparison to previously reported carbazole based macrocycles. Macrocycle 8 bearing a furan ring reversibly binds aqueous Hg2+ with high affinity over other Mn+ ions. The limit of detection (LOD) is ca. 100 nM. Hg2+ binding was confirmed via X-ray diffraction analysis.
Subject(s)
Carbazoles/chemistry , Mercury/analysis , Porphyrins/chemistry , Density Functional Theory , Ions/analysis , Models, Molecular , Molecular Structure , Photochemical Processes , Porphyrins/chemical synthesisABSTRACT
Vibronic-coupling effects play a key role for excited-state charge- and energy-transfer processes in organic molecular systems. Here, we demonstrate how the Jahn-Teller effect in triplet excited states of highly symmetric cycloparaphenylenes triggers an indirect intersystem crossing deactivation pathway. Strong Jahn-Teller distortion in the doubly degenerate second excited triplet state (T2) brings the molecular system energetically close to the lowest triplet state (T1), thereby opening the possibility for an extremely rapid internal conversion. Quantum dynamics simulations reveal an initial T2 â T1 population decay within 50 fs. Experimental observation of size-dependent intersystem crossing rates of cycloparaphenylenes is explained based on the proposed S1 â T3/T2 â T1 mechanism.
ABSTRACT
A 5-fold-interpenetrated zinc-based coordination polymer can discriminately detect aliphatic amines through a fluorescence "turn-on" method. This compound can sense aliphatic amines in the solid state, solution state, and vapor phase. Theoretical calculations revealed that the ground-state dipole moment of the corresponding amines guides the order of enhancement.