ABSTRACT
Enantioselective electroanalysis, which aims to discriminate the enantiomers of electroactive chiral probes in terms of potential difference, is a very attractive goal. To achieve this, its implementation is being studied for various "inherently chiral" selectors, either at the electrode surface or in the medium, yielding outstanding performance. In this context, the new inherently chiral monomer Naph2T4 is introduced, based on a biaromatic atropisomeric core, which is advantageously obtainable in enantiopure form without HPLC separation steps by a synthetic route hinging on enantiopure 2,2'-dibromo-1,1'-binaphthalenes. The antipodes of the new inherently chiral monomer can be easily electrooligomerized, yielding inherently chiral electrode surfaces that perform well in both cyclic voltammetry (CV) enantiodiscrimination tests with pharmaceutically interesting molecules and in magnetoelectrochemistry experiments.
Subject(s)
Computational Chemistry/methods , Naphthalenes/chemistry , Chromatography, High Pressure Liquid , Electricity , Electrodes , Stereoisomerism , ThermodynamicsABSTRACT
Two new inherently chiral oligothiophenes characterized by the atropisomeric 3,3'-bithianaphtene scaffold functionalized with fused ring bithiophene derivatives, namely 4H-cyclopenta[2,1-b3:4b']dithiophene (CPDT) and dithieno[3,3-b:2',3'-d]pyrrole (DTP), were synthesized. The racemates were fully characterized and resolved into antipodes by enantioselective HPLC. The enantiomers were analyzed through different chiroptical techniques: electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were employed to attribute the absolute configuration (AC). Comparison of experimental and calculated VCD spectra confirmed the DFT calculated conformational characteristics. The compound functionalized with two CPDT units was oxidized with FeCl3 , and ECD and CPL of the resulting material were measured. Circularly polarized luminescence (CPL) was measured to verify if inherently chiral oligothiophenes could be promising systems for chiral photonics applications.
Subject(s)
Models, Molecular , Thiophenes/chemistry , Chromatography, High Pressure Liquid , Circular Dichroism , Electrochemical Techniques , Molecular Conformation , Quantum Theory , Spectrophotometry, Ultraviolet , Stereoisomerism , Thiophenes/chemical synthesisABSTRACT
The racemate of an inherently chiral "spider-like" octathiophene monomer T83 , in which chirality is generated by torsion in its backbone, was synthesized. The racemate was resolved into configurationally stable antipodes by HPLC on a chiral stationary phase. Electrooxidation of the enantiomers resulted in materials displaying high enantiorecognition ability towards the antipodes of some chiral probes. Moreover, the T83 racemate demonstrated great aptitude to stimulate formation of 3D rigid architectures if used as a cross-linking monomer for molecular imprinting. This feature was exploited to devise a molecularly imprinted polymer-based chemosensor selective for a thymine-adenine oligonucleotide.
