RESUMEN
Significant effort has been devoted to the development of materials that combine high electrical conductivity and permanent porosity. This paper discloses a diazaporphyrin-based hydrogen-bonded organic framework (HOF) with porosity and n-type semiconductivity. A 5,15-diazaporphyrin Ni(ii) complex with carboxyphenyl groups at the meso positions afforded a HOF due to hydrogen-bonding interactions between the carboxy groups and meso-nitrogen atoms. The thermal and chemical stabilities of the HOF were examined using powder X-ray diffraction analysis, and the charge-carrier mobility was determined to be 2.0 × 10-7 m2 V-1 s-1 using the flash-photolysis time-resolved microwave conductivity (FP-TRMC) method. An analogous diazaporphyrin, which does not form a HOF, exhibited mobility that was 20 times lower. The results presented herein highlight the crucial role of hydrogen-bonding networks in achieving conductive pathways that can tolerate thermal perturbation.
RESUMEN
Oligothiols are useful as building blocks in the construction of disulfide-based macrocycles and polymers or as ligands for coordination polymers. Above all, benzenehexathiol (BHT) is a particularly important molecule, as it is used to construct conductive two-dimensional MOFs. Despite the desire to clarify its structure and isolate it to high purity, the chemical instability of BHT has hampered single-crystal X-ray structure analysis of intact BHT. In addition, the synthesis of discrete disulfide molecules of BHT has not been reported. Here, we succeed in obtaining the single crystals of intact BHT, which is analyzed by single crystal X-ray structure analysis. Furthermore, the structures of a group of molecules with intermolecular disulfide bonds (BHT·4im and BHT2·2TBA, im = imidazole, TBA = tetrabutylammonium cation) obtained by processing BHT in the presence of bases are determined.
RESUMEN
N,N'-dihydroxy-1,4,5,8-naphthalenetetracarboxdiimide (NDI-(OH)2 ) has attracted much attention in recent years, because its doubly deprotonated state, (O-NDI-O)2- , has metal-coordination ability and characteristic electronic transition useful for designing electronic and optical functions. In contrast, a molecular crystal with the mono-deprotonated (HO-NDI-O)- ion remains unknown. We herein report an organic crystal containing non-disproportionated (HO-NDI-O)- ions, which are connected by very strong O-H-O hydrogen bonds. Its lowest energy absorption band (450 to 650â nm) is observed in between that of NDI-(OH)2 (380â nm) and isolated (O-NDI-O)2- (500 to 850â nm) species, consistent with the molecular orbital calculations. This absorption originates from the electronic transition from deprotonated imide-based orbitals to NDI-core orbitals, which can be influenced by the hydrogen bonds around imide group. Consequently, the optical properties of NDI-(OH)2 can be modulated by the stepwise deprotonation and hydrogen-bonding interactions.
RESUMEN
Electrical conduction among metallocycles has been unexplored because of the difficulty in creating electronic transport pathways. In this work, we present an electrocrystallization strategy for synthesizing an intrinsically electron-conductive metallocycle, [Ni6(NDI-Hpz)6(dma)12(NO3)6]·5DMA·nH2O (PMC-hexagon) (NDI-Hpz = N,N'-di(1H-pyrazol-4-yl)-1,4,5,8-naphthalenetetracarboxdiimide). The hexagonal metallocycle units are assembled into a densely packed ABCABC sequence (like the fcc geometry) to construct one-dimensional (1D) helical π-stacked columns and 1D pore channels, which were maintained under the liberation of H2O molecules. The NDI cores were partially reduced to form radicals as charge carriers, resulting in a room-temperature conductivity of (1.2-2.1) × 10-4 S cm-1 (pressed pellet), which is superior to that of most NDI-based conductors including metal-organic frameworks and organic crystals. These findings open up the use of metallocycles as building blocks for fabricating conductive porous molecular materials.
RESUMEN
Preliminary chemical reduction of naphthalenediimide (NDI)-based organic ligands was applied to the synthesis of a porous molecular conductor (PMC) with neutral metal nodes (cobalt(ii) acetylacetonate). The obtained semiconductive PMC (PMC-2) was stable due to the neutral metal nodes, providing an advantage over electrochemical reduction.