Tetrazole compounds have been studied for more than one hundred years and applied in various areas. Several years ago Sharpless and his co-workers reported an environmentally friendly process for the preparation of 5-substituted 1H-tetrazoles in water with zinc salt as catalysts. To reveal the exact role of the zinc salt in this reaction, a series of hydrothermal reactions aimed at trapping and characterizing the solid intermediates were investigated. This study allowed us to obtain a myriad interesting metal-organic coordination polymers that not only partially showed the role of the metal species in the synthesis of tetrazole compounds but also provided a class of complexes displaying interesting chemical and physical properties such as second harmonic generation (SHG), fluorescence, ferroelectric and dielectric behaviors. In this tutorial review, we will mainly focus on tetrazole coordination compounds synthesized by in situ hydrothermal methods. First, we will discuss the synthesis and crystal structures of these compounds. Their various properties will be mentioned and we will show the applications of tetrazole coordination compounds in organic synthesis. Finally, we will outline some expectations in this area of chemistry. The direct coordination chemistry of tetrazoles to metal ions and in situ synthesis of tetrazole through cycloaddition between organotin azide and organic cyano group will be not discussed in this review.

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Multistate density functional theory (MSDFT) is presented to estimate the effective transfer integral associated with electron and hole transfer reactions. In this approach, the charge-localized diabatic states are defined by block localization of Kohn–Sham orbitals, which constrain the electron density for each diabatic state in orbital space. This differs from the procedure used in constrained density functional theory that partitions the density within specific spatial regions. For a series of model systems, the computed transfer integrals are consistent with experimental data and show the expected exponential attenuation with the donor–acceptor separation. The present method can be used to model charge transfer reactions including processes involving coupled electron and proton transfer.

A mononuclear ruthenium(II) polypyridyl complex with an enlarged terpyridyl coordination cage was synthesized by the formal introduction of a carbon bridge between the coordinating pyridine rings. Structurally, the ruthenium(II) complex shows an almost perfect octahedral N6 coordination around the central Ru(II) metal ion. The investigation of the photophysical properties reveals a triplet metal-to-ligand charge transfer emission with an unprecedented quantum yield of 13% and a lifetime of 1.36 mus at room temperature and in the presence of air oxygen. An exceptional small energy gap between light absorption and light emission, or Stokes shift, was detected. Additionally, time-dependent density functional theory calculations were carried out in order to characterize the ground state and both the singlet and triplet excited states. The exceptional properties of the new compound open the perspective of exploiting terpyridyl-like ruthenium complexes in photochemical devices under ambient conditions.

Changing stripes: The spin‐transition compound 1 can be nanopatterned by unconventional and soft lithography to give crystalline, well‐oriented, μm‐scale structures arranged in stripes on a silica surface. These findings have potential applications in electronic devices and information storage.

Applying the density matrix renormalization group (DRMG) method to a nonempirical valence bond (VB) model Hamiltonian, we studied polyacene oligomers of different lengths in the strong electron correlation limit. Geometrical optimizations were performed for the lowest singlet and triplet states of oligomers up to [40]-acene, and a convergence of the bond lengths toward the polymer limit is observed in the interior of the oligomer. For large oligomers, as well as for the polymer, the ground state can be reasonably determined to be a singlet. Furthermore, a high similarity between the singlet geometries and triplet geometries suggests an open-shell character for the singlet ground state. A reasonable speculation of the soliton-antisoliton pair character of the singlet ground state was supported by a spin distribution analysis of the triplet state wave function of large oligomers, with each of the two solitons being broadly delocalized over the upper or bottom edge of the oligomers, respectively.

We describe a diabatic-at-construction (DAC) strategy for defining diabatic states to determine the adiabatic ground and excited electronic states and their potential energy surfaces using the multistate density functional theory (MSDFT). The DAC approach differs in two fundamental ways from the adiabatic-to-diabatic (ATD) procedures that transform a set of preselected adiabatic electronic states to a new representation. (1) The DAC states are defined in the first computation step to form an active space, whose configuration interaction produces the adiabatic ground and excited states in the second step of MSDFT. Thus, they do not result from a similarity transformation of the adiabatic states as in the ATD procedure; they are the basis for producing the adiabatic states. The appropriateness and completeness of the DAC active space can be validated by comparison with experimental observables of the ground and excited states. (2) The DAC diabatic states are defined using the valence bond characters of the asymptotic dissociation limits of the adiabatic states of interest, and they are strictly maintained at all molecular geometries. Consequently, DAC diabatic states have specific and well-defined physical and chemical meanings that can be used for understanding the nature of the adiabatic states and their energetic components. Here we present results for the four lowest singlet states of LiH and compare them to a well-tested ATD diabatization method, namely the 3-fold way; the comparison reveals both similarities and differences between the ATD diabatic states and the orthogonalized DAC diabatic states. Furthermore, MSDFT can provide a quantitative description of the ground and excited states for LiH with multiple strongly and weakly avoided curve crossings spanning over 10 Å of interatomic separation.

The reactions of 2-, 3-, and 4-cyanopyridine with NaN(3) in the presence of H(2)O and Lewis acid (ZnCl(2)) afford discrete monomer, (2-PTZ)(2)Zn(H(2)O)(2) (1), 3D diamondoid-like network (3-PTZ)(2)Zn (2), and 2D layered network (4-PTZ)Zn(OH)(H(2)O) (3), respectively (PTZ = 5-(pyridyl)tetrazolato). Their solid state structures and natures give new insight into the Sharpless reaction of 5-substituted 1H-tetrazole. Interestingly, 2 crystallizes in a noncentrosymmetric space group and its powdered sample is second-harmonic generation active.