J. Appl. Cryst.の発刊に際して

Interpretation of europium(III) spectra

Supramolecular design of one-dimensional coordination polymers based on silver(I) complexes of aromatic nitrogen-donor ligands

The term nonlinear optics (NLO) was coined to describe the nonlinear relationship between dielectric polarization P and electric field E in optical media. NLO is a cornerstone of the emerging field of photonics, in which photons instead of electrons are used for signal transmission and processing. The vision of photonic signal transmission, processing, and storage has attracted a great deal of attention from both the engineering and the scientific communities because of its great impact in many of the existing and future information technologies. The first step toward realization of these revolutionary technologies is to develop tools to manipulate photons. For example, it is desirable to develop materials with the ability to alter the frequency of light, to amplify light signal, and to modulate light intensity or phase factors. NLO phenomena can be the key to achieving these important functions. One of the most common NLO behaviors is second-harmonic generation (SHG), in which a NLO material mediates the “adding-up” of two photons to form a new one with twice the frequency. The SHGphenomenonwas first demonstrated by Franken et al. in 1961. In their pioneering work, a laser beam with a wavelength of 694.2 nm was irradiated through a quartz crystal and an output ultraviolet radiation with a wavelength of 347.1 nm (double frequency) was detected. After this discovery, numerous nonlinear optical phenomena have been studied and a number of NLO-active materials have been developed. Second-harmonic generation can be quantitatively described by the second-order nonlinear optical susceptibility χ, a third-rank tensor with 27 components. The tensor elements are related to each other tomeet the requirements of both inherent and structural symmetries, which greatly reduces the number of independent components of the susceptibility tensor. Only crystals in noncentrosymmetric crystal classes can have nonvanishing χ. Moreover, for material crystallizing in the noncentrosymmetric 422, 622, and 432 crystal classes, the second-order NLO response might also vanish due to structural symmetry as well as Kleinman’s symmetry. Many inorganic compounds crystallize in noncentrosymmetric space groups and have been found to be SHG active. Some important examples are potassium dihydrogen phosphate (KDP = KH2PO4), lithium niobate (LiNbO3), and barium sodium niobate (Ba2NaNb5O15). 7 New inorganic compounds have been explored for NLO applications including but not limited to metal borates 12 and metal oxides. Recent structural studies on the inorganic systems have led to a better understanding of crystal growth/packing, paving the way for potentially manipulating their crystallization tendency to form noncentrosymmetric structures. Since the 1970s molecular NLO materials, including organic, organometallic, and inorganic complexes, have been of increasing interest to synthetic chemists. 19 The existing library of organic compounds was first screened, and the urea crystal has become a SHG standard because of its high SHG efficiency and usual availability. In a microscopic view, the second-order NLO susceptibility χ is related to the first hyperpolarizability β of a molecule. According to the classical two-level model, β is enhanced by a large transition moment and a large dipole moment difference between the ground and the charge transfer excited state. A donor acceptor type of molecule often possesses both a large transition moment and a large excited state dipole moment. As a result, most of the organic SHG chromophors belong to this category. However, most of the molecules with large β values also possess a large dipole moment, which induces formation of centrosymmetric assemblies of molecules due to dipole dipole interactions. One of the methods to avoid the centrosymmetric alignment of molecular dipoles is to trap them inside the channels of asymmetric porous host structures. 28 Other methods include formation of poled polymers in which the required asymmetry is imposed by the external electric field 35 and the Langmuir Blodgett (LB)

Rational synthesis of noncentrosymmetric metal-organic frameworks for second-order nonlinear optics.

Organotin(IV)n+ complexes formed with biologically active ligands: equilibrium and structural studies, and some biological aspects

In the structure of the title compound, C 24 H 24 O 2 , one of the two types of six-membered rings is planar and the other is in a skew-boat conformation. The ethylene C=C bond distance is 1.345 (3) A. The substituents at the ethylene are in an E configuration. The crystal structure consists of discrete molecules lying about inversion centres, held together by van der Waals contacts.

http://journals.iucr.org/c/issues/1999/11/00/sk1314/sk1314.pdf

(E)‐1,2‐Bis(3,4‐dihydro‐1‐methoxynaphthalen‐2‐yl)ethylene

The Schiff base ligand in the title complex, [Pt(C9H8BrN2S2)2], is deprotonated from its tautomeric thiol form and coordinated to PtII via the mercapto S and β–N atoms. The configuration about PtII is a perfect square-planar, with two equivalent Pt—N [2.023 (3) A] and Pt—S [2.293 (1) A] bonds. The phenyl ring is twisted against the coordination moiety Pt1/N1/N1′/S2′/S2 by 31.8 (2)°, due to the steric hindrance induced by ortho-substituted bulky Br atom.

Bis­[S-methyl 3-(2-bromo­benzyl­idene)­di­thio­cab­aza­to-N3,S]­platinum(II)

The pyrrolidine ring in the title mol­ecule, C23H21N3O, adopts a half-chair conformation. In the solid state, C—H⋯N intermolecular hydrogen bonds link inversion-related mol­ecules, forming cyclic dimers. The structure is further stabilized by weak C—H⋯O hydrogen bonds and van der Waals forces.

6-(4-Methoxy­phenyl)-4-phenyl-2-(pyrrolidin-1-yl)­nicotino­nitrile

The title molecule, C 30 H 26 N 2 O 6 S, consists of a methyl-pyrrolo[3,4-b]indole ring with a phenylsulfonyl, a phenyl and a dimethyl maleate group as exocyclic substituents. The pyrrolo[3,4-b]indole ring system is planar. The S atom has distorted tetrahedral geometry. The dihedral angle between the pyrrolo[3,4-b]indole and the phenylsulfonyl group is 65.2 (4) and it is 75.69 (1)° with the phenyl group. The sum of angles at the indole-N atom is 341.7°, while the second pyrrole ring N atom adopts sp 2 hybridization. The packing is stabilized by weak C-H...O hydrogen bonds.

http://journals.iucr.org/c/issues/1999/08/00/os1056/os1056.pdf

Dimethyl α-(2-benzyl-1-methyl-4-phenylsulfonylpyrrolo[3,4-b]indol-3-yl)maleate

The structure of the title compound, C 27 H 25 N 5 O-0.5C 6 H 6 , has been determined from X-ray diffraction data. The compound crystallizes from benzene in the triclinic system, space group P1, with two molecules in the asymmetric unit. The naphthyridine ring system is almost planar and the six-membered piperidine ring adopts a chair conformation. Intramolecular N-H interactions are observed in the system with an N...π(phenyl centroid) distance of 3.619 (3) A, and C-H...π interactions between the naphthyridine molecule and the solvent are also observed.

Intramolecular N—H⋯π(phenyl) and intermolecular C—H⋯π(phenyl) interactions in 5-amino-4-(4-methoxyphenyl)-2-phenyl-7-piperidino-1,6-naphthyridine-8-carbonitrile--benzene(2/1)

S. Shanmuga Sundara Raj

Papers

(E)‐1,2‐Bis(3,4‐dihydro‐1‐methoxynaphthalen‐2‐yl)ethylene

Bis[S-methyl 3-(2-bromobenzylidene)dithiocabazato-N3,S]platinum(II)

6-(4-Methoxyphenyl)-4-phenyl-2-(pyrrolidin-1-yl)nicotinonitrile

Dimethyl α-(2-benzyl-1-methyl-4-phenylsulfonylpyrrolo[3,4-b]indol-3-yl)maleate

Intramolecular N—H⋯π(phenyl) and intermolecular C—H⋯π(phenyl) interactions in 5-amino-4-(4-methoxyphenyl)-2-phenyl-7-piperidino-1,6-naphthyridine-8-carbonitrile--benzene(2/1)

S. Shanmuga Sundara Raj

Papers

(E)‐1,2‐Bis(3,4‐dihydro‐1‐methoxynaphthalen‐2‐yl)ethylene

Bis­[S-methyl 3-(2-bromo­benzyl­idene)­di­thio­cab­aza­to-N3,S]­platinum(II)

6-(4-Methoxy­phenyl)-4-phenyl-2-(pyrrolidin-1-yl)­nicotino­nitrile

Dimethyl α-(2-benzyl-1-methyl-4-phenylsulfonylpyrrolo[3,4-b]indol-3-yl)maleate

Intramolecular N—H⋯π(phenyl) and intermolecular C—H⋯π(phenyl) interactions in 5-amino-4-(4-methoxyphenyl)-2-phenyl-7-piperidino-1,6-naphthyridine-8-carbonitrile--benzene(2/1)

Bis[S-methyl 3-(2-bromobenzylidene)dithiocabazato-N3,S]platinum(II)

6-(4-Methoxyphenyl)-4-phenyl-2-(pyrrolidin-1-yl)nicotinonitrile