Lin-Ping Zhang

Novel lanthanide(III) coordination networks based on 1,2-bis(4-pyridyl)ethane-N, N'-dioxide and trans-1,2-bis(4-pyridyl)ethene-N, N'-dioxide

The new ligand 1,2-bis(4-pyridyl)ethane-N,N′-dioxide (L) was used to generate five lanthanide(III) coordination networks of three structural types: (i) the isomorphous pair {[Ln(L)3]·(ClO4)3·(H2O)}∞ (Ln = Er, 1; Yb, 2) comprises two interpenetrating α-polonium nets in which each lanthanide(III) ion is in a rare homoleptic distorted octahedral coordination environment; (ii) an unprecedented mat-like pattern of three interwoven (6,3) nets is found in isomorphous {[Ln(NO3)3(L)1.5]·H2O}∞ (Ln = Er, 3; Yb, 4); (iii) {[La(NO3)3(L) (CH3OH)]· CH3OH·CH2Cl2}∞, 5, is built of an offset stacking of distorted square grids. The complex [Er(L′)0.5(H2O)3(C2O4)](ClO4)·L′·6H2O·(dioxane)0.5 (L′ = trans-1,2-bis(4-pyridyl)ethene-N,N′-dioxide), 6, is composed of (6,3) nets in which the Er(III) ions are bridged by both L′ ligands and oxalate ions.

Structural diversity in lanthanum(III) coordination polymers constructed with the isomeric flexible double betaines 1,4-bis(n-picolyloxyl)benzene-N, N'-diacetate (n = 2, 3)

Abstract Six coordination polymers: {[La(H2O)6L1]2Cl6·12H2O}∞ (1), [La(H2O)2L1(NO3)3]∞ (2), {[La(H2O)4(L1)2](CF3SO3)3·H2O}∞ (3), {[La(H2O)7(L2)0.5]Cl3}∞ (4), {[La(H2O)2L2(NO3)2]NO3·0.5H2O}∞ (5) and {[La(H2O)3(L2)2](CF3SO3)3·6H2O}∞ (6) have been synthesized by the reaction between lanthanum(III) salts and the isomeric double betaines 1,4-bis(2-picolyloxyl)benzene-N,N′-diacetate (L1) and 1,4-bis(3-picolyloxyl)benzene-N,N′-diacetate (L2). Compound 1, 2 and 3 are all mononuclear: 1 shows a double-layer network constructed by ML1 coordination bonds together with hydrogen bonds, while 2 and 3 are 3D frameworks. In compound 4, 5 and 6, dinuclear units are linked by one, two and four L2 ligands, respectively, leading to different kinds of polymeric chains; in each compound the chains are further connected through intermolecular hydrogen bonding and π–π stacking to generate a 2D network.

Coordination networks generated from transition metal chlorides and a flexible double betaine

Abstract The new flexible double betaine 1,4-bis(2-picolyloxyl)benzene-N,N′-diacetate (L) has been synthesized and used to generate five complexes with divalent metal chlorides: [M(H2O)6]Cl2·L·2H2O (M=Mn (1), Co (2)), [Cu(μ-L)Cl2]∞ (3), {[Zn(μ-L)Cl2]·2H2O}∞ (4), and {[Cd2(μ-Cl)2(μ-L)Cl2(H2O)2]·2H2O}∞ (5). Isomorphous compounds 1 and 2 have a hydrogen-bonded three-dimensional network in which adjacent L ligands overlap through π–π stacking of the pyridine and benzene rings. Compounds 3, 4, and 5 display three different types of one-dimensional polymeric structures. Bridged by L acting in the anti mode, compound 3 exhibits an infinite zigzag chain in which consecutive, approximately planar L ligands are arranged in a crossed manner when viewed along the chain direction, the distance between adjacent copper(II) ions being about 13 A. In contrast, compound 4 features a spring-like infinite helical chain with zinc ions lying on the axis and bridged by L acting in the syn fashion, and the Zn(II)⋯Zn(II) separation is approximately 9 A. In compound 5, the building unit is a centrosymmetric Cd2Cl2 moiety, and adjacent dimeric units are linked by the centrosymmetric L ligand acting in the anti mode to give an infinite zigzag chain running along the c axis; such chains are further connected through hydrogen bonds to form a three-dimensional network.