Structural Studies of Penetrated Ion Pairs Using Chiral Cyanine Borates

An induced circular dichroism (CD) spectrum is observed for 1,1$\sp\prime,3,3,3\sp\prime,3\sp\prime$-hexamethyl-9-phenyl-indo-carbocyanine, 1,1$\sp\prime$-diethyl-2,2$\sp\prime$-cyanine, 1,1$\sp\prime$-di-(3,5-di-tert-butyl)benzyl-2,2$\sp\prime$-cyanine, or 1,1$\sp\prime$-di-(4-tert-butyl)benzyl-2,2$\sp\prime$-cyanine when penetrated into a chiral cavity of either spirobi- ((2-methyl)borataxanthene) or spirobi- ((3-methyl)borataxanthene). Within the ion pair, the cyanine dye exists in two (or more) interconverting conformations of unequal energy. Solid state structural evidence suggests that a nitrogen-forward mode for penetration by the cyanine dominates the solution behavior. A critical feature for the detection of the induced circular dichroism spectrum is that the dye is twisted in the ground state. The free energy difference between the diastereomers with right- and left-handed twist in the chiral cavity of the borate is less than 1 kcal/mol, but this is sufficient to induce the CD spectrum. The magnitude of observed CD spectrum is dependent on the structure of both the cyanine and borate.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Owen, David John

Contributors dc:contributor

• Schuster, Gary B.

• Chemistry, Organic

Language dc:language

eng

Identifier

(MiAaPQ)AAI9834726

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84402