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Based on various comparable salen ligands, three synthesized CuIINaI-complexes present efficient catalytic activities for the coupling and cyclization reaction of 1,2-diaminopropane with nitriles towards 2-imidazolines. The catalytic results show that salen ligands with an electron-donating substituent and small steric hindrance improve the catalytic activity. [ABSTRACT FROM AUTHOR]

A new ligand, rac-(R,S)-3,9-bis(pyridin-3-yl)-2,4,8,10-tetraoxaspiro[5.5]undecane ((R,S)-bptu), is synthesized, and five novel complexes, namely, {[Cu[(R,S)-bptu]Cl2]·0.5NMP}n (1), {[Zn[(R,S)-bptu]Cl2]·CH3CN}n (2), {Cd2[(R,S)-bptu]2Cl4(NMP)2}n (3), {[Cd[(R,S)-bptu]2Cl2]·2CH3CN}n (4), and {Cd3[(R,S)-bptu]2Cl6(DMF)2}n (5), (NMP = N-methyl-2-pyrrolidone, DMF = N,N-dimethylformamide), are obtained via a layered diffusional reaction. (R,S)-bptu and complexes 1–5 are characterized by single-crystal X-ray diffraction, element analyses, powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). Complexes 1–3 show three different 1D structures: 1 is a mesomeric looped chain, 2 is a racemic helix compound, and 3 is a mesomeric zigzag chain, while 4 and 5 are two different mesomeric 2D structures, of which 4 is a 2D wave-like layer and 5 is a 2D cellular layer. Structural diversity indicates that the coordination preferences (cis- and trans-configurations) of (R,S)-bptu play a leading role in the self-assembly of complexes: cis-bptu tends to form one-dimensional structures 1–3, while trans-bptu is easier to construct higher dimensional structures 4–5. Secondly, the different transition metal atom M(ii) adopts diverse geometry in 1–5: Cu(ii) adopts square pyramidal geometry in 1, Zn(ii) employs a tetrahedron configuration in 2, and especially in 3–5, Cd(ii) displays a trigonal bipyramidal configuration, cis-cis–trans, cis and trans octahedral configuration. Finally, the different solvent system, the coordinated/free solvent, and the secondary building units (SBUs) affect the diversification of the structure. A variable temperature magnetic susceptibility investigation manifests that antiferromagnetic interactions exist between the neighbouring metal ions in 1. Furthermore, the luminescence properties of 2–5 are investigated in the solid state at room temperature, and 4 shows highly selective and sensitive sensing for Fe3+ ions. [ABSTRACT FROM AUTHOR]

Oxalic acid is believed to play an important role in the formation and growth of atmospheric organic aerosols. However, as a common organic acid, the understanding of the larger clusters formed by gas phase oxalic acid with multiple ammonia molecules is incomplete. In this work, the structural characteristics and thermodynamics of oxalic acid clusters with up to six ammonia molecules have been investigated at the PW91PW91/6-311++G(3df,3pd) level of theory. We found that oxalic acid forms relatively stable clusters with ammonia molecules, and that ionization events play a key role. The analyses of the thermodynamics and atmospheric relevance indicate that the heterodimer (H2C2O4)(NH3) shows an obvious relative concentration in the atmosphere, and thus likely participates in new particle formation. However, with increasing number of ammonia molecules, the concentration of clusters decreases gradually. Additionally, clusters of oxalic acid with ammonia molecules are predicted to form favorably in low temperature conditions and show high Rayleigh scattering intensities. [ABSTRACT FROM AUTHOR]

Based on various comparable salen ligands, three synthesized CuIINaI-complexes present efficient catalytic activities for the coupling and cyclization reaction of 1,2-diaminopropane with nitriles towards 2-imidazolines. The catalytic results show that salen ligands with an electron-donating substituent and small steric hindrance improve the catalytic activity.

A new ligand, rac-(R,S)-3,9-bis(pyridin-3-yl)-2,4,8,10-tetraoxaspiro[5.5]undecane ((R,S)-bptu), is synthesized, and five novel complexes, namely, {[Cu[(R,S)-bptu]Cl2]·0.5NMP}n (1), {[Zn[(R,S)-bptu]Cl2]·CH3CN}n (2), {Cd2[(R,S)-bptu]2Cl4(NMP)2}n (3), {[Cd[(R,S)-bptu]2Cl2]·2CH3CN}n (4), and {Cd3[(R,S)-bptu]2Cl6(DMF)2}n (5), (NMP = N-methyl-2-pyrrolidone, DMF = N,N-dimethylformamide), are obtained via a layered diffusional reaction. (R,S)-bptu and complexes 1-5 are characterized by single-crystal X-ray diffraction, element analyses, powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). Complexes 1-3 show three different 1D structures: 1 is a mesomeric looped chain, 2 is a racemic helix compound, and 3 is a mesomeric zigzag chain, while 4 and 5 are two different mesomeric 2D structures, of which 4 is a 2D wave-like layer and 5 is a 2D cellular layer. Structural diversity indicates that the coordination preferences (cis- and trans-configurations) of (R,S)-bptu play a leading role in the self-assembly of complexes: cis-bptu tends to form one-dimensional structures 1-3, while trans-bptu is easier to construct higher dimensional structures 4-5. Secondly, the different transition metal atom M(ii) adopts diverse geometry in 1-5: Cu(ii) adopts square pyramidal geometry in 1, Zn(ii) employs a tetrahedron configuration in 2, and especially in 3-5, Cd(ii) displays a trigonal bipyramidal configuration, cis-cis-trans, cis and trans octahedral configuration. Finally, the different solvent system, the coordinated/free solvent, and the secondary building units (SBUs) affect the diversification of the structure. A variable temperature magnetic susceptibility investigation manifests that antiferromagnetic interactions exist between the neighbouring metal ions in 1. Furthermore, the luminescence properties of 2-5 are investigated in the solid state at room temperature, and 4 shows highly selective and sensitive sensing for Fe3+ ions.