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Full-Text Articles in Physical Sciences and Mathematics
Cucurbit[8]Uril Rotaxanes, Vijayakumar Ramalingam, Adam R. Urbach
Cucurbit[8]Uril Rotaxanes, Vijayakumar Ramalingam, Adam R. Urbach
Chemistry Faculty Research
The synthesis of [2]rotaxanes, each comprising a viologen core threaded through a cucurbit[8]uril (Q8, Figure 1) macrocycle and stoppered by tetraphenylmethane groups, and their binding to second guests as inclusion complexes in organic and aqueous media are described. Stoppering was observed to have little effect on binding. Chemical modification of the threaded guest was used to control solubility and binding characteristics, thus demonstrating a novel approach to making artificial receptors with readily modifiable properties.
Reduction Of Benzylidene Dibenzo[ A, D ]Cycloheptenes: Over-Reduction Of Antiaromatic Dianions To Aromatic Tetraanions, Blakely Tresca, Macdonald Higbee, Nancy S. Mills
Reduction Of Benzylidene Dibenzo[ A, D ]Cycloheptenes: Over-Reduction Of Antiaromatic Dianions To Aromatic Tetraanions, Blakely Tresca, Macdonald Higbee, Nancy S. Mills
Chemistry Faculty Research
The antiaromaticity of a series of dianions of p-substituted benzylidene dibenzo[a,d]cycloheptenes was examined through calculated measures of antiaromaticity. The nucleus-independent chemical shifts (NICS) and magnetic susceptibility exaltation both showed substantial antiaromatic character in the benzannulated tropylium anion. When the antiaromaticity was normalized for the area of the ring, these tropylium anions were shown to be among the most antiaromatic anions in the chemical literature. Attempts to make the dianion through reduction with lithium or potassium gave the tetraanion as the only species observable in the (1)H NMR spectrum. Quench of the reaction mixture with trimethylsilyl chloride or D(2)O confirmed the …