Themed collection International Year of Crystallography Celebration: India

Welcome to this CrystEngComm themed issue celebrating the 2014 International Year of Crystallography in India.

Soft-oxometalates or soft states of oxometalates are discussed from the stand-points of their syntheses, structure, stabilization mechanism, reasons for formation and their interactions with sound and light leading to controlled motion and patterning.

The reactions of a flexible bidentate ligand 1,3-phenylene diisonicotinate (L) with Cu(I/II) salts afforded coordination polymers with varied dimensionalities and guest inclusion capabilities.

1D pharmaceutical solids composed of caffeine, carbamazepine and glibenclamide drugs show optical waveguiding tendency.

A new C₃ symmetric tripodal fluorescent organic molecule-based self-assembly-assisted supramolecular architecture has been designed and synthesised, which displayed a unique capsular cavity formed by multi-molecular aggregation.

Five new methyl and halogen derivatives of triaryl sulfonylhydrazone were synthesized to understand polymorphism and isostructurality upon Cl–Me and inter-halogen exchange. Conformational rigidity and sulfonamide dimer synthon control the isostructurality in this family of crystal structures.

Three Co based Zeolitic Imidazolate Frameworks (Co-ZIF-68, -69 and -81) which adopt a GME topology with high porosity have been synthesized. These Co-ZIFs show high CO₂ (273 K/298 K) uptake compared to their isostructural Zn based analogues.

Two Cd(II) based 3D frameworks exhibit interesting structural features and adsorption properties based on the linker functionality modulation.

A para-nitrophenyl functionalized C_3v symmetric flexible tripodal amide ligand, L, shows remarkable solvent dependent dual binding behaviour towards the octahedral hexafluorosilicate anion in solid state.

We report herein the first example of a single-crystal grown from a steroid-based organogel matrix.

The conformation of the carboxymethyl arms of a C₃-symmetric tricarboxylic acid was found to be influenced by the acyclic substituents of the secondary ammonium cations in the corresponding salts as revealed by their single crystal structures.

Furosemide–Na–trihydrate displayed aqueous solubility of about 4000 fold higher than that of furosemide while furosemide–K–monohydrate has over 10 000 times improved solubility.

A rigid 3-connecting triacid MeBTB was designed and synthesized in the quest of guest inclusion in the pores of honeycomb network structures generated based on the acid dimer-mediated self-assembly.

CdSe quantum dots have been embedded on the disk-like matrices obtained by self-assembly of two disk-like tripeptides. Photoelectric study in ambient light demonstrates that the conductivity of the nanoconjugate has enhanced by 200 orders of magnitude compared to that of CdSe.

The linker coordination angles observed in the crystal structures of a new series of coordination polymers of flexible linkers, are correlated with their dimensionality and topology.

A fluoride selective fluorophenyl attached triamide receptor shows encapsulation of halide in a C_3v-symmetric tripodal cleft stoppered by a solvent molecule.

A novel noncentrosymmetric 3D co-ordination polymer with a dia-net constructed under hydrothermal conditions exhibits intriguing 10-fold mutual entanglements and ferroelectric properties.

Four new MOFs of Zn(II) with different degrees of interpenetration have been synthesized using trans,trans-muconic acid and different N,N′-donors.

Three coordination polymers of Zn(II) were synthesized using an N,N′-donor ligand and various aliphatic dicarboxylates. The gas adsorption and photoluminescence of these compounds have also been investigated.

In the preparation of theophylline cocrystals, phenol coformers facilitate water assimilation due to their weaker O–H⋯N(imidazole) synthon. The presence of –COOH prevents water incorporation and provides added physical stability at high humidity. This study shows the feasibility of cocrystal design of an API to tune physical properties based on hydrogen bond synthons.

Three flexible magnetic metal–organic frameworks (MOFs) have been synthesized and their magnetic and adsorption properties were investigated.

The propensity of carboxyl⋯pyridyl synthon is more than carboxyl⋯pyridyl N-oxide synthon, but carboxyl⋯pyridyl N-oxide synthon forms shorter hydrogen bond than carboxyl⋯pyridyl synthon. Carboxyl⋯pyridyl N-oxide synthon containing systems might show better solubility than the corresponding carboxyl⋯pyridyl synthon containing systems.

Three new three-dimensional hybrid compounds, Ln₂(μ₃-OH)(C₄H₄O₅)₂(C₄H₂O₄)]·2H₂O, (Ln = Ce, Pr and Nd) (I²O¹-type) exhibiting proton conductivity and multi-photon up-conversion behaviour have been described.

Novel crystalline forms of voriconazole are identified with improved aqueous solubility. The dinitrate salt of voriconazole exhibited 10 fold higher solubility and 3 times faster dissolution rate in 0.1 N HCl medium compared to the reference drug.

Co-crystal screening of the anti-HIV drug lamivudine was carried out with dicarboxylic acids as co-formers. Salts of cytosine, a molecule that incorporates critical structural features of lamivudine, with the same co-formers, were taken as model systems for IR spectroscopic studies of the synthons in the salts of lamivudine.

We employ a fast evaporation crystallization method to identify two new solvates from acetone and tetrahydrofuran of succinylsulfathiazole (SST), as well as determined single crystal structures for previous unsolved forms. SST adopts exclusively the imidine form in all its crystalline forms.