Structural Studies of Penetrated Ion Pairs Using Chiral Cyanine Borates

Owen, David John

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https://hdl.handle.net/2142/84402 Copy

Description

Title

Structural Studies of Penetrated Ion Pairs Using Chiral Cyanine Borates

Author(s)

Owen, David John

Issue Date

1998

Doctoral Committee Chair(s)

Schuster, Gary B.

Department of Study

Chemistry

Discipline

Chemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Chemistry, Organic

Language

eng

Abstract

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.

Graduation Semester

1998

Type of Resource

text

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