Reaction of β-amino-β-(pyrid-4-yl)acrylonitrile with the aromatic dicarboxaldehydes 9,10-bis(4-formylphenyl)anthracene and terephthalaldehyde affords the dihydropyridyl products 9,10-bis(4-((3,5-dicyano-2,6-dipyridyl)dihydropyridyl)phenyl)anthracene (L(1)) and 1,4-bis(4-(3,5-dicyano-2,6-dipyridyl)dihydropyridyl)benzene (L(2)), respectively. In the solid state [L(1)]·2.5DMF·3MeOH (SOF-1) crystallizes in the monoclinic space group P2(1)/c and forms a 3D stable supramolecular organic framework via strong N-H···N(py) hydrogen bonds and π-π interactions. The material incorporates pyridyl-decorated channels and shows permanent porosity in the solid state. The pore volumes of the desolvated framework SOF-1a calculated from the N(2) isotherm at 125 K and the CO(2) isotherm at 195 K are 0.227 and 0.244 cm(3) g(-1), respectively. The N(2) absorption capacity of SOF-1a at 77 K is very low, with an uptake of 0.63 mmol g(-1) at 1 bar, although saturation N(2) adsorption at 125 K is 6.55 mmol g(-1) (or 143 cm(3) g(-1)). At ambient temperature, SOF-1a shows significant CO(2) adsorption with approximately 3 mol of CO(2) absorbed per mole of host at 16 bar and 298 K, corresponding to 69 cm(3) g(-1) at STP. SOF-1a also adsorbs significant amounts of C(2)H(2), with an uptake of 124 cm(3) (STP) g(-1) (5.52 mmol g(-1)) at 1 bar at 195 K. Methane uptake at 195 K and 1 bar is 69 cm(3) (STP) g(-1). Overall, gas adsorption measurements on desolvated framework SOF-1a reveal not only high capacity uptakes for C(2)H(2) and CO(2), compared to other crystalline molecular organic solids, but also an adsorption selectivity in the order C(2)H(2)> CO(2) > CH(4) > N(2). Overall, C(2)H(2)(270 K)/CH(4)(273 K) selectivity is 33.7 based on Henry's Law constant, while the C(2)H(2)(270 K)/CO(2)(273 K) ratio of uptake at 1 bar is 2.05. The less bulky analogue L(2) crystallizes in the triclinic space group P1 as two different solvates [L(2)]·2DMF·5C(6)H(6) (S2A) and [L(2)]·2DMF·4MeOH (S2B) as pale yellow tablets and blocks, respectively. Each L(2) molecule in S2A participates in two N-H···O hydrogen bonds between dihydropyridyl rings and solvent DMF molecules. Packing of these layers generates 1D nanochannels along the crystallographic a and b axes which host DMF and benzene molecules. In S2B, each L(2) ligand participates in hydrogen bonding via an N-H···O interaction between the N-H of the dihydropyridyl ring and the O of a MeOH and also via an N···H-O interaction between the N center of a pyridine ring and the H-O of a second MeOH molecule. The presence of the L(2)-HOMe hydrogen bonds prevents ligand-ligand hydrogen bonding. As a result, S2B crystallizes as one-dimensional chains rather than as an extended 3D network. Thermal removal of solvents from S2A results in conversion to denser phase S2C which shows no effective permanent porosity.

The unique bifunctional porous metal-organic framework, [Co(HL dc )]$1.5MeOH$dioxane, incorporates both free-standing carboxyl and pyridyl groups within its pores. Gas adsorption measurements on the desolvated framework reveal unusual selective CO 2 adsorption over C 2 H 2 and CH 4 linked to a framework phase change from a narrow pore (np) to a large pore (lp) form, mediated by CO 2 uptake at 195 K. This phase transition has been monitored by in situ powder X-ray diffraction and IR spectroscopy, and modelled by Grand Canonical Monte Carlo simulations revealing that the reversible np to lp transition is linked to the rotation of pyridyl rings acting as flexible ''pore gates''. Scheme 1 In situ decarboxylation of H 4 L to give [HL dc ] 2À in 1 and 2, and view of binding of [HL dc ] 2À to Co(II) showing non-coordinated pendant acidic and basic sites (Co: turquoise; O: red; N: blue; C: grey; H: white).

A series of zero-to three-dimensional Cd/Zn(II)-1,2,4-triazolate coordination complexes have been obtained by changing the anions and the substituents on the triazole ring. Cd 2 (2-pytrz) 2 Cl 4 (1) and Cd 3 (dpatrz) 4 Cl 6 (2) (2-pytrz ) 3,5-di(pyrid-2-yl)-1,2,4triazole and dpatrz ) 3,5-di(n-propyl)-4-amino-1,2,4-triazole) have discrete binuclear and trinuclear structures, respectively. Cd 3 (atrz) 4 Cl 6 (3) and Cd(atrz) 2 (SCN) 2 (4) (atrz ) 4-amino-1,2,4-triazole) are polymeric 1D chains constructed from trinuclear cadmium units and mononuclear cores. Cd(datrz)I ( 5), Zn(dmtrz)Cl ( 6), and Cd 3 (dmatrz) 4 (N 3 ) 6 (7) (datrz ) 3,5-diamino-1,2,4-triazole, dmtrz ) 3,5-dimethyl-1,2,4-triazole, and dmatrz ) 3,5-dimethyl-4-amino-1,2,4-triazole) all show two-dimensional layer structures. Complexes 5 and 6 are 2D grids based on binuclear clusters and present (4.8 2 ) metal (4.8 2 ) trz topology. Complex 7 is of 2D (4,4) topology when trinuclear cadmium units are regarded as four-connected nodes. For complexes 1-7, weak hydrogen-bonding contacts link the discrete polynuclear clusters, 1D chains, or 2D layers to form three-dimensional supramolecular structures. Zn 2 (trz) 3 Cl (8) (trz ) 1,2,4-triazole) presents an interesting 3D network based on three nonequivalent nodes and has a (4 6 8 6 12 24 )(8 6 12 54 )(4 2 8 4 12 36 ) 3 topology. Complexes 1-8 all exhibit strong blue fluorescence emission bands in the solid state at ambient temperature.