A Novel Zeolite-Induced Population of a Planar Viologen Conformation. New Viologen Charge Transfer Complexes and Alkene/Viologen/Zeolite Arrays

Abstract

A rare example of a novel zeolite-induced conformational change and a mechanism for this process are suggested in order to rationalize an unexpected spontaneous intrazeolite reduction observed during preparation of a new viologen (MQ 2+ )-doped zeolite (NaY). In addition, the formations of six new alkene/viologen/ zeolite charge transfer (CT) arrays using NaMQY and the previously reported NaMVY are also reported. The binding constants between MQ 2+ and MV 2+ and 2,3-dimethyl-2-butene (TME) were determined using the Benesi-Hildebrand approach, and the stabilities of these CT complexes are compared to their intrazeolite analogue.

Syntheses, Characterizations, and Properties of Electronically Perturbed 1,1‘-Dimethyl-2,2‘-bipyridinium Tetrafluoroborates

“…Addition of 2,3-dimethyl-2-butene to the 2,2‘-bipyridinium ions resulted in formation of a shoulder on the red edge of each absorption spectrum consistent with charge transfer (CT) formation. Benesi−Hildebrand analysis of the charge-transfer complexes in CH 3 CN gave equilbrium constants ( 1 , 0.16 ± 0.06 M -1 ; 2 , 0.58 ± 0.08 M -1 ; 3 , 0.20 ± 0.03 M -1 ) of the same order of magnitude as observed previously for MQ 2+ . The lack of correlation of K eq with the electronic character of the substituent suggests that steric effects also play a role in the stabilities of these CT complexes.…”

Synthesis, Characterization, Photophysics and Photochemistry of Pyrylogen Electron Transfer Sensitizers

“…Charge transfer complexes of the other pyrylogens with PDMB are not as readily apparent and are only observed as a broad shoulder on the long wavelength side of the pyrylogen UV–Vis spectrum. This hypsochromic shift with decreasing thermodynamic stability of the complex is a well‐established phenomenon and serves as confirmation for the assignment of these bands to CT complexes . The long‐wavelength edges of the CT bands in conjunction with a Benesi–Hildebrand analysis demonstrates that these are weak complexes (0.2 < K eq < 1).…”

Preparation and Photochemistry of Single Wall Carbon Nanotubes Having Covalently Anchored Viologen Units

“…This color clearly indicates the presence of a CT complex between the bipyridinium cation as acceptor and iodide as electron donor. These types of halide−viologen complexes are well documented in literature, particularly when iodide is the accompanying halide due to its lower ionization potential. − To avoid the formation of this CT complex we proceeded to ion exchange iodide with PF 6 - using a saturated aqueous solution of ammonium hexafluorophosphate. The presence of I - and the formation of the CT complex between V and I - may play an undesirable influence on the interaction of V with the walls of the SWNT, thus modifying the efficiency of photochemical events.…”