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In organic field-effect transistors (OFETs), the quality of charge-transport pathway, controlled by crystal structures of organic semiconductors (OSCs), strongly affects the performance of the device. To achieve higher charge mobility, solution-processed single-crystal (SPSC) techniques have been used to decrease crystal defects by aligning the crystals of OSCs in the in-plane direction. Nonetheless, through SPSC techniques, whether the crystalline lattices are well-aligned in the out-of-plane direction and how the out-of-plane lattice misorientaion affects OFET performances remain unclear. Here, a characterization protocol based on polarized optical microscope, X-ray diffraction, and electron diffraction is established to identify the lattice structure, the in-plane and out-of-plane lattice alignment in the crystal array of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN). Regardless of the solvents used in the PDMS-assisted crystallization, the characterization protocol confirms that all the crystal arrays share the same lattice structure (form I phase), and have similar in-plane lattice alignment. However, TIPS-PEN molecules have sufficient time to unify their out-of-plane orientation and prevent the formation of low angle grain boundary (LAGB) during crystal growth if high boiling temperature solvents are used. The improved out-of-plane lattice alignment increases the hole mobility and decreases the performance fluctuations of devices. The results confirm that the out-of-plane lattice alignment significantly impacts the performance of the devices and the reproducibility of the solution-processed TIPS-PEN OFETs. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of Cu(NO3)2 and 2-isopropylimidazole (Hipim) in different solvents/templates gave three supramolecular isomers: α-[Cu(ipim)] (1), β-[Cu(ipim)] (2), and γ-[Cu(ipim)]·1/3C6H6 (3). Single-crystal X-ray diffraction analyses showed that 1, 2, and 3 are parallel-packed wavy chains, triple-stranded helices, and cubic-orthogonal-packed helical chains consisting of alternatively interconnected two-coordinated Cu(I) ions and ipim- ligands. Because of the different intermolecular interactions, 1, 2, and 3 show different phosphorescence properties with emission maxima at 555, 540, and 530 nm, respectively. More interestingly, [Cu(ipim)] can melt at high temperature without decomposition. Compounds 1 and 2 melt above 185 and 146 °C, respectively; this liquid solidifies below 117 °C to form 1 again. However, 3 loses the benzene guest molecules above 90 °C and transforms to 1 in a crystal-to-crystal manner. [ABSTRACT FROM AUTHOR]

Self-assembly of silver(I) ion with 3-alkyl-1,2,4-triazoles in different solvents yielded four new metal azolate frameworks (MAFs), namely, [Ag(mtz)] (1, Hmtz = 3-methyl-1,2,4-triazole), [Ag(etz)] (2, Hetz = 3-ethyl-1,2,4-triazole), [Ag4(etz)4]·H2O (3·H2O), and [Ag4(ptz)4] (4, Hptz = 3-propyl-1,2,4-triazole). Single-crystal X-ray diffraction revealed that Ag(I) ions and triazolates in these MAFs are all three-coordinated to give rare 3-connected framework topologies. Although 1and 2possess the same uniform (10,3)-d (utp) topology, variation of the alkyl groups renders substantially different coordination structures. On the other hand, 3·H2O and 4, also bearing different alkyl substituents, are isomorphours, and can be simplified as the same uninodal sqc5603 topology (point and vertex symbols are 82.10 and 8.82.12, respectively). Due to the relatively short alkyl length, the coordination framework of 3·H2O contains one-dimensional narrow channels. According to thermogravimetry and single-crystal X-ray diffraction, 3·H2O can be dehydrated without framework collapse. Although guest-free 3does not adsorb N2at 77 K, 3·H2O can undergo guest exchange, and 3can adsorb solvent vapor, to give CH2Cl2- and CH3CN-included crystals. Comparing the single-crystal structures of 3·H2O, 3, 3·CH2Cl2, and 3·CH3CN reveals the framework flexibility of 3. These materials also show interesting structure- and guest-dependent photoluminescent properties. [ABSTRACT FROM AUTHOR]