Biology Reference
In-Depth Information
The analyte affinity is a matter of primary concern in the
design of a sensor. The artificial receptors bind guest molecules
by a combination of fundamental electrostatic, hydrogen bonding,
and van der Waals interactions. These interacting molecular forces
can be controlled to affect molecular recognition by means of
host
guest complementarity and host preorganization [14,15]. The
preorganization leads to stronger and more selective binding as
well as increasing rigidity. The sensor rigidity can hinder the analyte
from binding sites hence the sensor rigidity should be balanced with
flexibility as well as the binding site and the event reporter should be
structurally integrated as much as possible in order to maximize the
communication. A versatile means of communication to generate
such an event is provided by transition metal coordination driven
metallacyclic supramolecules, in which the desired components can
be easily incorporated according to the needs of analyte to generate
analytically useful and observable signals. Self-assemblies driven
by transition metal coordination have been successfully applied to
construct numerous metallacyclic supramolecular structures with
interesting functions. The transition metal
−
−
containing macrocycles
are generally designed to be sensitive and responsive on electro- and
photochemical stimuli and the desired functionalities can be easily
incorporated into the metallacyclic supramolecular framework
by employing functional ligands and/or metal centers. The metal
centers may interact within the metallacyclic superstructure, thus,
leading to a higher level of collective functionality and the cavities
defined by the macrocycle may accommodate guest molecules. The
most significant features, which arise upon the formation of the
metallacyclic architecture, include encapsulation of guest molecules,
luminescence, and redox activity. Depending on the size and nature
of the cavities, these structures can act as a host for various types of
guest molecules of different sizes and shapes. A combination of the
differing host
−
guestbehaviorofvariousmetallacyclicsupramolecules
with their arising luminescent or electronic properties can, thus, be
exploited for sensing purposes. The inherent potential of metallacyclic
supramolecules thereby provides opportunities to develop novel
molecular devices. Substantial progress has been made in the past
few years in the area of functional metallacyclic supramolecular
assemblies and their use as recognition of analytes at molecular
level. There are several excellent review articles on the coordination-
driven metallacylic-supramolecular chemistry [16
−
19], as well as
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