The control of the orientation of liquid crystalline molecules is essential in liquid crystal displays (LCDs), and is usually achieved by coating an alignment film on the conductive ITO (indium tin oxide) glass surface. The photo-alignment (PA) technique as one promising alternative to the widely used conventional rubbing process of a polyimide (PI) substrate has been studied extensively in the last decade, because it provides a simple and non-contact fabrication process suitable for advanced thin film transistor (TFT) LCDs. In principle, the PA materials can be primarily divided into two categories based on the type of functional groups employed. The first ones are capable of undergoing photo-induced isomerization from trans isomer (E-isomer) to cis-isomer (Z-isomer) and vice versa; this category includes molecules such as azobenzene-containing polymers.[1] The second category consists of polymers that can be anisotropically photo-crosslinked on illumination with linear polarized ultraviolet (LPUV) light; this includes examples such as polymers containing cinnamoyl or coumarin groups. [2,3] In particular, Schadt, [2b±d] and O'Neill and Kelly [4] recently demonstrated that the films based on coumarin exhibit high sensitivities and high pretilt angles (up to 7.5), although the alignment was ascribed to unstable photo-degradation rather than cross-linking. However, despite the promising future of the PA technique, the search for materials possessing fine comprehensive performance still remains a great challenge.As an inorganic±organic hybrid, the ladder-like polysilsesquioxanes (LPSs) possess many excellent properties, such as being colorless and transparent, glasslike film-forming ability, high adhesion to glass and silicon chips, and superior solubility in common organic solvents, and are potentially ideal skeleton materials for PA applications. [5,6] Accordingly, a novel LPS containing dual photo-reactive groups, cinnamoyl and p-nitroazobenzene, attached in a side-on fashion, was synthesized (Scheme 1, which also shows the structure of the final polymer). The molecular design was based on the following considerations:l the azobenzene-containing polymer films often have a higher degree of tilted orientation and photosensitivity than the photo-cross-linking ones; [7] l the threshold dose required to obtain a superior alignment for the side-on azo-grafted polymer is substantially smaller than that of the end-on ones; [8] l both the photo-orientation and photo-cross-linking of the neighboring dual moieties would take place collaboratively after proper irradiation and most likely result in better alignment stability. As expected, the LC cell assembled using the LPS-CA30 coated substrates exhibits a uniformly homogeneous alignment (almost mono-domain) with a long temporal stability (over one year at room temperature) and an adjustable tilt angle (h = 1~7) by variance in UV-light intensity (2~5 mW cm ±2 ). The macroscopic orientation behavior of the LC cell was observed by polarizing optical microscopy (POM). It wa...

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Metal-containing (MC) liquid crystals are currently attracting a great deal of interest due to the perceived advantages of combining the properties of liquid-crystal systems with those of transition metals.[1±3] The emergence of bimetallomesogens remarkably expands the range of MC liquid crystals, and these mesogens can exhibit ferromagnetism and/or mixed oxidation states.[4±6] Recently, considerable attention has been focused on ªmacrodiscoticº mesogens possessing larger disc-shaped cores, which can potentially lead to well-ordered supramolecular structures with high charge-carrier mobilities.[7±9]Although various binuclear metallomesogens have been reported previously, only a few of these reports involve bimetallic macrodiscotic mesogens; the status of research using this type of metallomesogenic materials is still in its infancy.[3] As part of our continuing research on metallomesogens such as bis[l-(p-ethoxy-di(ethyleneoxy)phenyl)-3-(p-n-hexyloxyphenyl)propane-1,3-dionato] copper(II), C 6 EDK-Cu, [8] we report here a novel p-conjugated gemini-like bimetallic macrodiscogen (GBMM) with copper-bis(b-diketonate)-based twin cores. The synthesis of GBMM is summarized in Scheme 1. A macrodiscogen with m-phenylene-bridged twin cores has not been reported before, as far as we know. The phenylenebridged twin cores construct a central hole, which may provide the macrodiscogen with the ability to enclose guest molecules and ions and might afford potential technological applications in the field of molecular electronics, photonics, and ion transport. [9] As expected, a quasi-planar rectangle and a well-ordered flat supramolecular arrangement are observed from the scanning tunneling microscope (STM) images (Fig. 1), in which well-ordered patterns with parallel bright ridges and sur-COMMUNICATIONS 1534