Three new inorganic coordination polymers, {[Mn(H 2 O) 6 ]-[Mn 2 (H 2 O) 6 ][(Cu 6 (mna) 6 ]•6H 2 O}, 1, {[Mn 4 (OH) 2 (H 2 O) 10 ][(Cu 6 (mna) 6 ]• 8H 2 O}, 2, and {[Mn 2 (H 2 O) 5 ][Ag 6 (Hmna) 2 (mna) 4 ]•20H 2 O}, 3, have been synthesized at room temperature through a sequential crystallization route. In addition, we have also prepared and characterized the molecular precursor [Cu 6 (Hmna) 6 ]. Compounds 1 and 3 have a two-dimensional structure, whereas 2 has a three-dimensional structure. The formation of 2 has been achieved by minor modification in the synthetic composition, suggesting the subtle relationship between the reactant composition and the structure. The hexanuclear copper and silver cluster cores have Cu•••Cu and Ag•••Ag distances close to the sum of the van der Waals radii of Cu 1+ and Ag 1+ , respectively. The connectivity between [Cu 6 (mna) 6 ] 6− cluster units and Mn 2+ ions gives rise to a brucite related layer in 1 and a pcu-net in 2. The [Ag 6 (Hmna) 2 (mna) 4 ] 4− cluster in 3, on the other hand, forms a sql-net with Mn 2+ . Compound 1 exhibits an interesting and reversible hydrochromic behavior, changing from pale yellow to red, on heating at 70 °C or treatment under a vacuum. Electron paramagnetic resonance studies indicate no change in the valence states, suggesting the color change could be due to changes in the coordination environment only. The magnetic studies indicate weak antiferromagnetic behavior. Proton conductivity studies indicate moderate proton migrations in 1 and 3. The present study clearly establishes sequential crystallization as an important pathway for the synthesis of heterometallic coordination polymers.

Amine templated three-dimensional zinc-organophosphates with different ring sizes have been obtained by varying the organic amine molecules. The figure shows the various net structures obtained during the study.

The reaction of uranyl acetate dihydrate with 2,5thiophenedicarboxylic acid (H 2 TDC) as the main ligand and pyrazine (PYZ); piperazine (PZ); 1,4 pyridyl piperazine (PYPZ); 1,4-di(pyridin-4yl) piperazine (DPYZ); 1,2 pyrimidyl piperazine (PMPZ) as auxiliary ligand leads to the formation of five new compounds [UO 2 (TDC)-They were analyzed by IR, UV−vis, thermogravimetric analysis, X-ray diffraction analysis, powder X-ray diffraction, and fluorescence spectroscopy. Depending on the countercation, uranyl thiophene dicarboxylate is shown to crystallize as 2D layer in (I, IV), 2D layer with twofold interpenetrated (6,3) nets in (II), 1D chains in (III), and 2D layer without 2-fold interpenetrated (6,3) nets in (V). The coligand DPYZ in structures of (III and IV) had not been added to the reaction but has been formed by the N-arylation of the PYPZ ligand. Compound (IV) was obtained serendipitously while trying some mixed metal compound. Furthermore, their functional properties, photoluminescence, and photocatalytical activity for oxidation of organic dyes have also been studied. Interestingly, compounds (II and V) with uranyl organic frameworks (UOF's) and honeycomb (6,3) nets possess highest efficiency in degradation of dyes.

An organic solid, 4,7-dibromo-5,6-dinitro-2,1,3-benzothiadiazole, has been designed to serve as an illustrative example to quantitatively evaluate the relative merits of halogen and chalcogen bonding in terms of charge density features. The compound displays two polymorphic modifications, one crystallizing in a non-centrosymmetric space group (Z' = 1) and the other in a centrosymmetric space group with two molecules in the asymmetric unit (Z' = 2). Topological analysis based on QTAIM clearly brings out the dominance of the chalcogen bond over the halogen bond along with an indication that halogen bonds are more directional compared to chalcogen bonds. The cohesive energies calculated with the absence of both strong and weak hydrogen bonds as well as stacking interaction are indicative of the stabilities associated with the polymorphic forms.

Three new metal-organic porphyrinic framework compounds of zinc and 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TPyP) have been synthesized under solvothermal conditions. The compounds [Zn (C H N )(C H O ) (NO ) (DMA) ] (DMA) (H O) (1; DMA=dimethylacetamide), [Zn (C H N )(C H O ) (DMF)](DMF) (H O) (2), and [Zn (C H N )(C H O ) (DMA) ](H O) (3) have two (1) and three dimensionally (2 and 3) extended structures. All the three structures contain porphyrinic units connected through the carboxylate linkers. The nitrates bind the metal centers and are not hydrogen bonded. The different binding modes of nitrate in the structure of 1 are observed for the first time in a porphyrin-based MOF. The openness of the structure allowed us to explore metal exchange through a room-temperature metathetic route. Compound 2 undergoes 100 % exchange with copper, whereas compound 3 exchanges 70 % with copper. The copper-exchanged compounds Cu∈2 and Cu∈3 were observed to be good heterogeneous catalysts for many important organic reactions. The chemo and regioselective enamination of β-ketoesters, preparation of propargylamine derivatives as well as regioselective cycloadditions of alkyne and azide (click reactions) have been carried out with good yields and selectivity. All the compounds have been characterized by PXRD, IR, UV/Vis, atomic absorption spectroscopy (AAS), and energy-dispersive X-ray spectroscopy (for Cu exchange).

A new porphyrin-based compound, [Zn (C H N )(C H N O ) (DEF) ](DEF) (1; DEF=N,N-diethylformamide), has been synthesized by employing 5,10,15,20-tetrakis(4-pyridyl)porphyrin, 1,2-diamino-3,6-bis(4-carboxyphenyl)benzene, and Zn salt at 100 °C under solvothermal conditions. The structure, as determined by single-crystal XRD studies, is three-dimensional with threefold interpenetration. The usefulness of free -NH groups in the ligand was exploited for anchoring silver nanoparticles through a simple solution-based route. The silver-loaded sample, Ag@1, was characterized by powder XRD, energy-dispersive X-ray spectroscopy, high-resolution TEM, SEM, X-ray photoelectron spectroscopy, and inductively coupled plasma MS analysis, which clearly indicated that silver nanoparticles with a size of 3.83 nm were uniformly distributed within the metal-organic framework (MOF). The Ag@1 sample was evaluated for possible catalytic activity for the carboxylation of a terminal alkyne by employing CO under atmospheric pressure; this gave excellent results. The Ag@1 catalyst was found to be robust, active, and recyclable. The present studies suggest that porphyrin MOFs not only exhibit interesting structures, but also show good heterogeneous catalytic activity towards the fixation of CO .

Three new heterometallic metal organic frameworks, [{[Ca6(H2O)18]­[Ag6(mna)6]2}­·[Ag6(Hmna)6]­·20H2O], 1, {[Sr3(H2O)10]­[Ag6(mna)6]­·12H2O}, 2, and {[Ba3(H2O)10]­[Ag6(mna)6]­·8H2O}, 3, have been synthesized following hard–soft acids–bases principle. Compounds 1 and 2 have three-dimensional structures with cor and pcu (α-Po) topology, whereas compound 3 has a two-dimensional sql topology. Smaller calcium and strontium ions form a simple dimer (Ca2/Sr2, 1/2) and tetramer units (Sr4, 2), whereas the larger barium ion forms infinite Ba–O–Ba chains. The presence of the electron-rich mna ligand in all the compounds paved the way for the detection of electron-deficient hazardous nitroaromatics employing photoluminescence quenching methods. The luminescence intensities of the compounds are strongly quenched by picric acid, p-nitro phenol, and 2-nitro toluene at low concentration, which indicates that these compounds are excellent materials for the detection of these nitroaromatics in solution.

The ligand 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzoic acid was synthesized and employed for the synthesis of two metal–organic framework (MOF) compounds, [Mn4(C20H10N2O4S)2(HCOO)4(DEF)2] (I; DEF=N,N′‐diethylformamide) and [Pb(C20H10N2O4S)(DMF)] (II; DMF=N,N′‐dimethylformamide). Single‐crystal structure studies revealed that compound I has a three‐dimensional structure and compound II has a two‐dimensional structure. The luminescent nature of the MOFs was gainfully employed as a probe for the detection of highly toxic metal ions such as Tl3+ and Hg2+. The detection limits were found to be in the parts per billion (ppb) level. The presence of an unsubstituted thiadiazole ring in the ligand appears to help in the detection of these highly toxic metal ions in solution as the metal ions interact with S, which was revealed by Raman spectroscopic studies. The compounds were also found to be good candidates for the detection of highly oxidizing anions such as chromate, dichromate, and permanganate, again in ppb levels of concentration in solution. Magnetic studies on compound I indicate antiferromagnetic behavior. The variable‐temperature electrical conductivity studies indicate a semiconducting nature with comparable behavior to well‐known semiconductors such as CdSe, ZnTe, and GaP.