François Kajzar and Kwang-Sup Lee
The present issues (1.3-4) addresses the important class of materials which are chiral, optically active and attract an increasing interest because of their high potential for application in photonics and in electronics. Various applications of such materials include bio-imaging, optical signal processing, logic systems, magneto-optics, magnetic field sensing and bio-sensing, as well as brain wave detection. Among chiral materials are such important biopolymers like deoxyribonucleic acid (DNA), collagen as well as proteins. These materials are noncentrosymmetric, exhibiting second-order nonlinear optical properties, thus not requiring a particular processing as in the case of electro-optic polymers. As chiral materials they are expected also to exhibit important magneto-optic Faraday effect. The processing, functionalization and application of DNA in photonics is reviewed and discussed by J. Grote and co-workers.
A. Pawlicka and co-workers describe fabrication and characterization of DNA-surfactant complex based conducting membranes, doped with several organic chromophores, providing them different coloration and ionic conductivities. All solid DNA-CTMA-dye membranes exhibit photoluminescence with intensities in agreement with structural properties. They can be also used in electrochemical displays, smart windows and solar energy conversion as solid electrolytes. Observation of important magneto-optic effects in organic molecules is reported by T. Verbiest and A. Persoons. The authors report on very large Faraday rotation of light polarization being due to the magnetically induced circular birefringence. Its practical applications, particularly in magnetic field sensing, are reviewed and discussed.
The display applications of organic molecules using an alternating current are addressed by S.H. Cho et al. and Tada et al. Cho et al. present their work on electroluminescent devices driven by the alternating current electric fields. The paper gives a review of recent research developments in understanding alternating current light emission and describe the ways to improve the device performance such as, in particular, brightness, operation voltage, power efficiency, color mixing and tuning. Tada et al. describe realization of a real-time 3D display based on photo-sensitive azo dye molecules embedded in a polymer matrix. The observed high holographic performance with azo-carbazole derivatives is inferred as being a consequence of interaction between polymer chain and dopant molecules via the hydrogen bonding. Finally F. Hache presents a paper on using time-resolved circular dichroism method to study the dynamics of conformational changes in molecules. Such studies can yield a relevant information on the excitonic coupling, octant rule or the phenomenological relationship between the far-UV circular dichroism and the secondary structures of chiral molecules like proteins he has studied.
We hope this timely issue on chiral and optically active materials would contribute to their increasing understanding and applicability. We hope it would highlight the field and inspire scientists to further harness the properties of chiral molecules, polymers and their combinations.
Bucharest & Lyon