17340-32-8Relevant articles and documents
Room-temperature thermotropic ionic liquid crystals: Viologen bis(triflimide) salts
Bhowmik, Pradip K.,Han, Haesook,Nedeltchev, Ivan K.,Cebe, James J.
, p. 27 - 46 (2004)
Several dicationic salts with bis(triflimide) as counterions - otherwise known as viologens - were prepared by metathesis reaction of the corresponding viologen dibromides (diiodides) with lithium triflimide in a polar solvent. They were characterized for
Influence of Constitution and Charge on Radical Pairing Interactions in Tris-radical Tricationic Complexes
Cheng, Chuyang,Cheng, Tao,Xiao, Hai,Krzyaniak, Matthew D.,Wang, Yuping,McGonigal, Paul R.,Frasconi, Marco,Barnes, Jonathan C.,Fahrenbach, Albert C.,Wasielewski, Michael R.,Goddard, William A.,Stoddart, J. Fraser
, p. 8288 - 8300 (2016)
The results of a systematic investigation of trisradical tricationic complexes formed between cyclobis(paraquat-p-phenylene) bisradical dicationic (CBPQT2(?+)) rings and a series of 18 dumbbells, containing centrally located 4,4′-bipyridinium radical cationic (BIPY?+) units within oligomethylene chains terminated for the most part by charged 3,5-dimethylpyridinium (PY+) and/or neutral 3,5-dimethylphenyl (PH) groups, are reported. The complexes were obtained by treating equimolar amounts of the CBPQT4+ ring and the dumbbells containing BIPY2+ units with zinc dust in acetonitrile solutions. Whereas UV-Vis-NIR spectra revealed absorption bands centered on ca. 1100 nm with quite different intensities for the 1:1 complexes depending on the constitutions and charges on the dumbbells, titration experiments showed that the association constants (Ka) for complex formation vary over a wide range, from 800 M-1 for the weakest to 180 000 M-1 for the strongest. While Coulombic repulsions emanating from PY+ groups located at the ends of some of the dumbbells undoubtedly contribute to the destabilization of the trisradical tricationic complexes, solid-state superstructures support the contention that those dumbbells with neutral PH groups at the ends of flexible and appropriately constituted links to the BIPY?+ units stand to gain some additional stabilization from C-H?π interactions between the CBPQT2(?+) rings and the PH termini on the dumbbells. The findings reported in this Article demonstrate how structural changes implemented remotely from the BIPY?+ units influence their non-covalent bonding interactions with CBPQT2(?+) rings. Different secondary effects (Coulombic repulsions versus C-H?π interactions) are uncovered, and their contributions to both binding strengths associated with trisradical interactions and the kinetics of associations and dissociations are discussed at some length, supported by extensive DFT calculations at the M06-D3 level. A fundamental understanding of molecular recognition in radical complexes has relevance when it comes to the design and synthesis of non-equilibrium systems.
The antibacterial activity of 4,4′-bipyridinium amphiphiles with conventional, bicephalic and gemini architectures
Grenier, Melissa C.,Davis, Robert W.,Wilson-Henjum, Kelsey L.,Ladow, Jade E.,Black, Jacob W.,Caran, Kevin L.,Seifert, Kyle,Minbiole, Kevin P.C.
, p. 4055 - 4058 (2012)
Dialkyl 4,4′-bipyridinium compounds are widely employed for their useful redox properties, and are commonly known as viologens due to their intense coloration upon reduction. Despite their prevalence and amphiphilic nature, the antibacterial activity of these compounds remains largely unreported. We have thus prepared a series of mono- and bis-alkylated analogs of 4,4′-bipyridine to investigate structure-activity relationships in their inhibition of a battery of Gram positive and Gram negative bacteria. The prepared cationic compounds were conventional (one cationic head, one non-polar tail), bicephalic (two heads, one tail), or gemini (two heads, two tails) in their amphiphilic structure. Additionally, an isomeric series of six bis-alkylated compounds ranging from symmetric (PQ-11,11) to highly asymmetric (PQ-20,2) were prepared. Four themes of bioactivity emerged: (1) the most bioactive compounds were gemini in structure; (2) 22 carbons in the alkyl chains, with little to modest asymmetry, led to optimal activity; (3) bicephalic compounds were generally comparable to conventional amphiphiles, though only about 12 carbons in the alkyl chains were solubilized in water by each cationic nitrogen; (4) the effects of counterion identity were not evident between chlorides and bromides; however, the presence of the iodide counterion inhibited dissolution in all compounds tested. Three isomeric compounds with little to no asymmetry in tail length, PQ-11,11, PQ-12,10, and PQ-14,8, prepared as the bromide salts, showed comparable and highly potent activity, with MIC levels around 2 μM against 3 of 4 bacteria tested. The simple (one- to two-step) syntheses of potent antimicrobials portend well for future optimization.
Fulleropillar[4]arene: The Synthesis and Complexation Properties
Dai, Ling,Ma, Jingyu,Mi, Yan,Wu, Wanhua,Xiao, Chao,Yang, Cheng,Yao, Jiabin
supporting information, (2020/02/15)
A multihydroquinone ether dialdehyde derivative 2 was incidentally obtained through an unexpected ring opening of pillar[4]arene[1]quinone 1. And the Prato reaction of 2 with [60]fullerene led to [60]fullerene bisadducts, from which trans-4 cyclic regioisomer 3 was isolated and characterized. The fulleropillar[4]arene 3 showed a larger cavity and can accommodate a viologen derivative C12V2+with a much stronger affinity than permethyl pillar[5]arene (MP5) and pillar[4]arene[1]quinone 1.
