A novel molecular design concept to control the emission of a metal-organic framework, {Mg(DHT)(DMF)(2)}(n), (DHT: 2,5-dihydroxyterephthalate), based on excited state proton transfer (ESIPT) of the organic linker, DHT, is demonstrated. The framework unveils permanent porosity and exhibits ligand-based multicolor emission that can be tuned and well controlled by the solvent molecules in solution as well as in the solid state.

Three novel coordination polymers based on M2+ (M = Cu, Zn), pyrazine (pyz) and the SiF62– ion, [Cu(SiF6)(pyz)(H2O)2]n (1a), {[Cu(SiF6)(pyz)3]·2H2O}n (1b blabla 2H2O) and {[Zn(SiF6)(pyz)2]·2MeOH}n (2 blabla 2MeOH), have been synthesized and characterized by single‐crystal X‐ray diffraction analyses. Compound 1a forms straight one‐dimensional chains of–Cu(OH2)2–pyz–, which are bridged by SiF62– ions to produce two‐dimensional sheets. Compound 1b blabla 2H2O forms straight two‐dimensional sheets of –Cu(pyz)2–pyz– chains bridged by SiF62– ions, where perpendicularly protruding pyz planes are stacked to produce a three‐dimensional framework with 2.5 × 2.2 Å2 pores. In compound 2 blabla 2MeOH, grids of [Zn(pyz)2]n are bridged by SiF62– ions axially coordinating to Zn2+ ions to produce an open three‐dimensional framework. The 4.5 × 4.5 Å2 pores in 2 blabla 2MeOH are surrounded by pyz panels, and they remain intact after removal of solvents to give [Zn(SiF6)(pyz)2]n (2). The permanent porosity of 2 was characterized by adsorption studies with solvent vapours such as MeOH (kinetic diameter 3.8 Å), EtOH (4.3 Å), iPrOH (4.7 Å) and Me2CO (4.7 Å), showing a size‐exclusive effect at around 4.7 Å. Furthermore, the H2 adsorption/desorption isotherm of 2 at 77 K shows a sharp uptake with a slight hysteresis loop, which is attributed to both the small size of the pore and the interaction between H2 molecules and fluorine (SiF62–) atoms that are exposed on the pore surfaces. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A porous coordination polymer (PCP) has been synthesized employing an organic ligand in which a stable free radical, isoindoline nitroxide, is incorporated. The crystalline PCP possesses one-dimensional channels decorated with the nitroxyl catalytic sites. When O2 gas or air was used as the oxidant, this PCP was verified to be an efficient, recyclable, and widely applicable catalyst for selective oxidation of various alcohols to the corresponding aldehydes or ketones.

We herein report an unusual CO(2) adsorption behavior in a fluoro-functionalized MOF {[Zn(SiF(6))(pyz)(2)]·2MeOH}(n) (1) with a 1D channel system, which is made up of pyrazine and SiF(6)(2-) moieties. Surprisingly, desolvated 1 (1') adsorbs higher amounts of CO(2) at 298 K than at 195 K, which is in contrast to the usual trend. Combined Raman spectroscopic and theoretical studies reveal that slanted pyrazine rings in 1' with an angle of 17.2° with respect to the (200) Zn(II)-Si plane at low temperature block the channel windows and thus reduce the uptake amount.

Five new supramolecular metal-organic coordination polymers (MOCPs), {[Ni(bipy) 5) (bipy = 4,4 0 -bipyridyl; 2,6-nds = 2,6-naphthalenedisulphonate) have been synthesized and structurally characterized. Compounds 1 and 5 were synthesized at room temperature in H 2 O/EtOH medium, whereas 2-4 were isolated under hydrothermal conditions. Compounds 1-4 were synthesized maintaining the same stoichiometric ratio of metal and ligand under different reaction temperatures, and the different structures of the compounds indicate that the temperature plays a significant role in the construction of the coordination polymers. Structural characterization reveals that the one-dimensional [M(bipy)(H 2 O) 4 ] 2þ cationic chain is a basic building unit for all of the MOCPs, while 2,6-nds remains as a counteranion. In all cases, 2,6-nds counteranions interact with water and bipy molecules through strong hydrogen-bonding and π-π interactions to afford threedimensional supramolecular structures. Compounds 1-4 have the same building unit with different network superstructures and are related as supramolecular isomers. Supramolecular isomerism in 3 and 4 is very interesting since they have the same molecular formula, {[Ni(bipy)(H 2 O) 4 ](2,6-nds)}, and are polymorphs. Compounds 4 and 5 are isomorphous. The thermogravimetric study suggests that the dehydrated compounds are stable up to 300 °C. Furthermore, sorption studies suggest that dehydrated compounds of 1 and 2 are permanently porous.

A 3D porous Zn(II) metal-organic framework {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)(H(2)O)]·4H(2)O} (1; H(2)dht=dihydroxyterphthalate, azpy=4,4'-azobipyridine) has been synthesised by employing 2,5-dihydroxyterephthalic acid (H(4)dht), a multidentate ligand and 4,4'-azobipyridine by solvent-diffusion techniques at room temperature. The as-synthesised framework furnishes two different types of channels: one calyx-shaped along the [001] direction and another rectangle-shaped along the [101] direction occupied by guest water molecules. The dehydrated framework, {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)]} (1') provides 52.7% void volume to the total unit-cell volume. The pore surfaces of 1' are decorated with unsaturated Zn(II) sites and pendant hydroxyl groups of H(2)dht linker, thereby resulting in a highly polar pore surface. The dehydrated framework 1' shows highly selective adsorption of CO(2) over other gases, such as N(2), H(2), O(2) and Ar, at 195 K. Photoluminescence studies revealed that compound 1 exhibits green emission (λ(max)≈530 nm) on the basis of the excited-state intramolecular proton-transfer (ESIPT) process of the H(2)dht linker; no emission was observed in dehydrated solid 1'. Such guest-induced on/off emission has been correlated to the structural transformation and concomitant breaking and reforming of the OH···OCO hydrogen-bonding interaction in the H(2)dht linker in 1'/1.

Two new 3-fold interpenetrated 3D microporous metal-organic coordination polymers (MOCPs) of Cu(II), [Cu 3 (bipy) 1.5 (2,6-ndc) 3 ] n (1) and {[Cu(bpe) 0.5 (2,6-ndc)] 3 0.5H 2 O} n (2) (bipy = 4,4 0 -bipyridine; bpe=1,2-bis(4-pyridyl)ethane; and 2,6-ndc=2,6-naphthalenedicarboxylate), have been synthesized using a mixed-ligand system and structurally characterized by single-crystal X-ray diffraction study. Roomtemperature reaction of Cu(II) with bipy and 2,6-ndc affords 1, whereas reaction with bpe and 2,6-ndc yields 2. Structure determination reveals that in both cases, a 2D square grid made by Cu(II) and 2,6-ndc with the aid of Cu 2 (CO 2 ) 4 paddlewheel building block is connected by bipy (1) or bpe (2) organic pillar results 3D R-polonium type frameworks. Framework 1 is rigid and robust without any guest molecules, whereas 2 is flexible, realized by the guest induced structural transformations. Both the frameworks show high thermal stability. Framework 1 and dehydrated form of 2, i.e 2 0 contains 16.6% and 21.4% void space, respectively and Langmuir surface area calculated from nitrogen adsorption study for 1 and 2 0 is 113.0 and 337.5 m 2 /g, respectively. Both the frameworks can store approximately 1 wt % of molecular hydrogen at 77 K and 15 bar, in particular, the density of adsorbed hydrogen in 1 is one of the highest reported so far in porous MOCPs. Compounds 1 and 2 0 can also store 11.0 and 13.2 wt % carbon dioxide at 195 K.

A new 2D pillared-bilayer porous coordination polymer (PCP) has been synthesized and structurally characterized that shows selective adsorption of CO(2) over other gases (N(2), O(2), Ar, H(2), CH(4)) and guest selective single/double-step adsorption of vapor correlated to the successive confinement of adsorbates in a 1D channel and a 2D interlayer space.