Enantioselective Recognition of Neutral Molecules in Water by a Pair of Chiral Biomimetic Macrocyclic Receptors

Enantioselective recognition in water remains an ongoing challenge in supramolecular chemistry but is routine in nature.Herein,we report the first enantiopure pair of biomimetic macrocyclic receptors with hydrogen bonding donors in their deep hydrophobic cavities.The chiral naphthotubes can be efficiently synthesized through a chirality-directed macrocyclization strategy and are able to discriminate the enantiomers of neutral chiral molecules in water.Density functional theory calculations reveal that the“three-point contact”model effectively explains their enantioselectivity.The differential noncovalent interactions inside the hydrophobic cavity are responsible for the enantioselective recognition.Moreover,these chiral naphthotubes are both fluorescent and circular dichroism(CD)-active.In CD spectroscopy,they have been demonstrated to have the ability to detect nonchromophoric,achiral molecules in water.And,the use of fluorescence spectroscopy has aided in the determination of the enantiomeric excess(ee)values of chiral molecules.The results and conclusions obtained with these chiral biomimetic receptors can be used to better understand enantioselective recognition in biological systems.

Bioinspired optical antennas: gold plant viruses

The ability to capture the chemical signatures of biomolecules(i.e.,electron-transfer dynamics)in living cells will provide an entirely new perspective on biology and medicine.This can be accomplished using nanoscale optical antennas that can collect,resonate and focus light from outside the cell and emit molecular spectra.Here,we describe biologically inspired nanoscale optical antennas that utilize the unique topologies of plant viruses(and thus,are called gold plant viruses)for molecular fingerprint detection.Our electromagnetic calculations for these gold viruses indicate that capsid morphologies permit high amplification of optical scattering energy compared to a smooth nanosphere.From experimental measurements of various gold viruses based on four different plant viruses,we observe highly enhanced optical cross-sections and the modulation of the resonance wavelength depending on the viral morphology.Additionally,in label-free molecular imaging,we successfully obtain higher sensitivity(by a factor of up to 10^(6))than can be achieved using similar-sized nanospheres.By virtue of the inherent functionalities of capsids and the plasmonic characteristics of the gold layer,a gold virus-based antenna will enable cellular targeting,imaging and drug delivery.

Information gathering and processing with fluorescent molecules

Molecular information gathering and proces- sing -- a young field of applied chemistry -- is undergoing good growth. The progress is occurring both in terms of conceptual development and in terms of the strengthening of older concepts with new examples. This review critically surveys these two broad avenues. We consider some cases where molecules emulate one of the building blocks of electronic logic gates. We then examine molecular emulation of various Boolean logic gates carrying one, two or three inputs. Some single-input gates are popular information gathering devices. Special systems, such as ＇lab-on-a-molecule＇ and molecular key- pad locks, also receive attention. A situation deviating from the Boolean blueprint is also discussed. Some pointers are offered for maintaining the upward curve of the field.