Single crystals of tetrakis(thiadiazole)porphyrazine and the corresponding metal(II) derivatives, MTTDPz (M=H2, Fe, Co, Ni, Cu, and Zn) were grown by sublimation under reduced pressure with continuous N2 gas flow. Their structures, obtained by X-ray crystallographic analysis, depend significantly on the central metal ion, and the M=Ni and Cu derivatives exhibit polymorphism. They can be classified into three forms, alpha, beta, and gamma. The alpha form (M=H2, Ni, and Cu) is composed of two-dimensional hexagonal close packing formed by side-by-side contacts between thiadiazole rings, whereas the beta form (M=Fe, Co, and Zn) crystallizes into a one-dimensional coordination polymer. The gamma form (M=Ni and Cu) consists of a ladder structure caused by pi stacking, similar to the beta form of phthalocyanine, and by side-by-side contacts between thiadiazole rings. Although the crystal structures of the MTTDPz series exhibited multi-dimensional network structures, magnetic measurements revealed relatively weak exchange interactions, probably reflecting the long distances between the metal ions.

Monometallic derivatives of tetrakis(1,2,5-thiadiazole)porphyrazine, [TTDPzH2], with main group tervalent metal ions having the formulae [TTDPzMX] (TTDPz = tetrakis(1,2,5-thiadiazole)porphyrazinato dianion; M = Al(III), X = Cl-, Br-, OH-; M = Ga(III), X = Cl-, OH-; M = In(III), X = AcO-) were prepared and investigated by single-crystal X-ray analysis and IR and UV-vis spectroscopy as well as cyclic voltammetry and spectroelectrochemistry. The complexes [TTDPzMX] (M = Al(III), X = Cl-, Br-; M = Ga(III), X = Cl-) were obtained by direct autocyclotetramerization of the precursor 3,4-dicyano-1,2,5-thiadiazole in hot quinoline in the presence of MX3 salts (M = Al(III), Ga(III); X = Cl-, Br-) and were hydrolized to form the corresponding hydroxide derivatives, [TTDPzMOH]. The In(III) complex, [TTDPzIn(OAc)], was obtained from the free-base macrocycle [TTDPzH2] with In(OH)(OAc)2 in CH3COOH. A single-crystal X-ray study was made at 173 K on the two isostructural species [TTDPzMCl] (M = Al(III), Ga(III)), which have space group P, with a = 12.470(14), b = 12.464(13), and c = 13.947(12) angstroms, alpha = 70.72(3), beta = 79.76(3), and gamma = 90.06(3) degrees, V = 2009.3(3) angstroms3, and Z = 4 for [TTDPzAlCl] and a = 12.429(3), b = 12.430(3), and c = 13.851(3) angstroms, alpha = 70.663(6), beta = 79.788(8), and gamma = 89.991(9) degrees, V = 1983.3(7) angstroms3, and Z = 4 for [TTDPzGaCl]. Square pyramidal coordination exists about the M(III) centers, with Cl- occupying the apical position (Al-Cl = 2.171(5) and Ga-Cl = 2.193(1) angstroms). Al(III) and Ga(III) are located at distances of 0.416(6) and 0.444(2) angstroms from the center of the N4 system. The molecular packing consists of stacked double layers with internal and external average interlayer distances of 3.2 and 3.3 angstroms, respectively. IR spectra show nu(Al-Cl) at 345 cm(-1) for [TTDPzAlCl], nu(Al-Br) at 330 cm(-1) for [TTDPzAlBr], and nu(Ga-Cl) at 382 cm(-1) for [TTDPzGaCl]. The UV-vis spectra in weakly basic (pyridine, DMF, DMSO) and acidic solvents (CF3COOH, H2SO4) show the typical intense pi --> pi transition bands in the Soret (300-400 nm) and Q-band regions (640-660 nm), the bands evidencing some dependence on the nature of the solvent, particularly in acidic solutions. Cyclic voltammetry, differential pulse voltammetry, and thin-layer spectroelectrochemical measurements in pyridine and dimethylformamide of the species [TTDPzMX] indicate reversible first and second one-electron reductions, whereas additional ill-defined reductions are observed at more negative potentials. The examined species are much easier to reduce than their phthalocyanine or porphyrin analogues as a result of the remarkable electron-attracting properties of the TTDPz macrocycle which contains annulated strongly electron-deficient thiadiazole rings.

The crystal structures and magnetic properties of heterocyclic thiazyl radicals and related materials have been examined. TTTA (=1,3,5-trithia-2,4,6-triazapentalenyl) exhibited a first-order phase transition between a paramagnetic high-temperature (HT) phase and a diamagnetic low-temperature (LT) phase, with a wide thermal hysteresis loop over the temperature range 230-305 K. The phase control of TTTA was achieved by pressure and by light irradiation. BDTA (=1,3,2-benzodithiazolyl) also exhibited a diamagnetic-paramagnetic phase transition above room temperature. However, fresh samples always exhibited a superheating of the LT phase that resulted in a double melting (melt-recrystallization-melt process) and supercooling of the HT phase, which in turn led to an antiferromagnetic ordering at 11 K. The molecular compounds of thiazyl radicals were prepared; TTTA formed a coordination polymer structure in the TTTA Á (M ¼ Ga and Fe), exhibited ferromagnetic ordering at 7 K and ferrimagnetic ordering at 44 K after evaporation of crystal solvents. We also grew crystals of M-TTDPz (TTDPz = tetrakis(thiadiazole)porphyrazine and M ¼ H 2 , Fe, Co, Ni, Cu, and Zn) and performed their structural analyses. Their crystal structures were found to depend strongly on the central metal ion and could be classified into three forms: , , and .The electrical and magnetic properties of molecular crystals have been studied extensively in the past three decades, and various molecule-based conductors, superconductors, and magnetic materials have been synthesized to date. The research has been characterized by the enhancement of dimensionality in intermolecular interactions. The first molecular metal, TTF-TCNQ, exhibited a Peierls transition due to instability of the 1D conducting pathway formed by the -overlap.

In this paper, the Joule heat welding of thin Pt wires with different diameters was performed and the current required for successful welding was investigated. The diameter of one wire was 800 nm and the others had various diameters of 1, 2, and 5 µm. Various combinations of wire lengths were used in the welding experiments. The minimum and maximum currents for successful welding were found to be highly dependent on the length of the 800 nm diameter wire. From these experimental results, it was inferred that the highest temperature in the system during welding occurred in some part of the 800 nm diameter wire and that the temperature in the larger diameter wire with sufficient heat capacity were almost unchanged. It was also found that the conditions for successfully welding wires of different diameter can be described by a parameter previously proposed for classifying the successful conditions for welding two 800 nm diameter wires.