A structural parameter to link molecular geometry to macroscopic orientation in discotic liquid crystals: study of metalloporphyrin tapes

Columnar liquid crystals based on antiaromatic expanded porphyrins

Three naphthorosarins, antiaromatic expanded porphyrins bearing different meso substituents (NRos 1-3), designed to self-assemble into columnar liquid crystalline (LC) structures, were synthesized and characterized using polarized optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), as well as supporting computational calculations. The substituents were found to play a crucial role in modulating the LC behaviour.

Metal Complexes of Singly, Doubly and Triply Linked Porphyrins and Corroles: An Insight into the Physicochemical Properties

Metal complexes of multi-porphyrins and multi-corroles are unique systems that display a host of extremely interesting properties. Availability of free meso and β positions allow formation of different types of directly linked bis-porphyrins giving rise to intriguing optical and electronic properties. While the fields of metalloporphyrin and corroles monomer have seen exponential growth in the last decades, the chemistry of metal complexes of bis-porphyrins and bis-corroles remain rather underexplored. Therefore, the impact of covalent linkages on the optical, electronic, (spectro)electrochemical, magnetic and electrocatalytic activities of metal complexes of bis-porphyrins and -corroles has been summarized in this review article. This article shows that despite the (still) somewhat difficult synthetic access to these molecules, their extremely exciting properties do make a strong case for pursuing research on these classes of compounds.

Dual-Axis Alignment of Bulk Artificial Water Channels by Directional Water-Induced Self-Assembly

Approaching single-crystal-like morphology has always been important in driving materials toward their optimal properties. With only orientational order, liquid crystal (LC) materials require dual-axis orientational control to optimize their structural order in the bulk phase. However, current external guiding fields such as electrical, magnetic, and mechanical guiding fields are less effective in aligning amphiphilic LCs. In this study, water is developed as an excellent structural stabilizer and orientation-directing agent of an amphiphilic discotic molecule (AD) in the water-induced self-assembly (WISA) process. Thermal analysis and structural characterization results show that water increases the stability and domain sizes of the hexagonal columnar (Col_h) phase of the AD by co-assembling with the ADs to form bulk artificial water channels (AWCs). Moreover, through control over the nucleation conditions (degree of supercooling and location of nucleation), dual-axis alignment in both the planar and vertical growth of the AWCs is achieved by applying water as the guiding field in the directional WISA. With precise control over the hierarchical structures, the bulk AWC array of the AD delivers excellent salt rejection properties and water permeability. Considering that all the amphiphilic LCs have hydrophilic segments, these new roles of water in the WISA process could launch the further development of functional amphiphilic LCs by providing a dynamic interaction and a readily available guiding field.