Multichannel Sensors Based on Biphenyl and Cyclohexane Conformational Changes - Designing Receptors for the Next Generation of Biosensors - page 2

Abbreviations

CD Circular dichroism

CV Cyclic voltammetry

DC2 Oxalate

DC3 Malonate

DC4 Succinate

DC5 Glutarate

DC6 Adipate

DMSO Dimethyl sulfoxide

HBA Hydrogen-bond acceptor

HBD Hydrogen-bond donor

MeCN Acetonitrile

SCE Standard carbon electrode

SQWV Square wave voltammetry

TBA Tetrabutylammonium

TBA( t -BuO) Tetrabutylammonium t -butoxide

TBAOH Tetrabutylammonium hydroxide

THF Tetrahydrofuran

TMA Tetramethylammonium

TMB Tetramethylbenzidine

1 Introduction

Molecular systems that combine binding ability and photophysical or electrochem-
ical properties are of much interest for designing chemosensors [ 1 - 13 ]. There are
different transduction mechanisms for transmitting the information of the complex-
ation event to the macroscopic world. Among these mechanisms, conformational
changes can be used to modify the ligand's photophysical or electrochemical
properties. In line with this, useful probes should be rigid enough to guarantee
one main conformation under the conditions of measurement. Additionally, those
probes that can be studied through two channels are more interesting as this helps
enhance selectivity and/or sensitivity.
Herein we summarize the use of several sensors based on biphenyl and cyclo-
hexane scaffolds (Fig. 1 ). Biphenyl can be used both as signaling unit and simulta-
neously as transduction moiety. Thus the dihedral angle formed between both
aromatic rings in the 2,2 0 -disustituted biphenyl system plays an important role in
the photophysical or electrochemical properties not only of the free ligand but
also of the corresponding complexes. So it was that both N. S. Finney [ 14 - 16 ] and
A. C. Benniston [ 17 ] demonstrated how conformational restriction is a feasible
mechanism for transducing ion binding into an enhanced fluorescence emission in
organic fluorophores. On the other hand, in appropriately substituted biphenyls,