Biomedical subjects

ML Tong

Publications and source records attributed to ML Tong.

4 recordsLinked to original sources

PubMed2000

Self-assembly of two- and three-dimensional coordination networks with hexamethylenetetramine and different silver(I) salts

Interesting two-dimensional networks with square or hexagonal cavities, and three-dimensional networks with different channels, have been obtained by varying the counterions, the molar ratio of metal to hmt (hmt = hexamethylenetetramine) and the pH values of the initial solutions. Among the eleven products isolated and structurally characterized, two have a metal-to-hmt molar ratio of 2:1 and are the first examples of Ag-hmt square networks, namely [Ag2(mu4-hmt)(NO2)2] (1) and [Ag2(mu4-hmt)(SO4)(H2O)].4H2O (2), two have a metal-to-hmt molar ratio of 1:1 and are 2-D networks with hexagonal cavities, namely [Ag(micro3-hmt)(NO2)] (3) and [Ag2(micro3-hmt)2](S2O6).2H2O (4), and seven present the metal-to-hmt molar ratios of 3:1, 2:1, 3:2, or 4:3 and are 3-D networks of novel topologies and with different channels, namely [Ag2(mu4-hmt)(micro4-ox)] (5), [Ag3(micro4-hmt)2(H2O)2](SO4)(HSO4). 2H2O (6), [Ag2(mu4-hmt)(mu2-O2CMe)](MeCO2).4.5 H2O (7), [Ag2(mu4-hmt)(mu3-maleate)].5H2O (8), [Ag3(mu4-hmt)(mu2-O2CPh)3] (9), [Ag4(mu4-hmt)3(H2O)](SO4)(NO3)2.3H2O (10), and [Ag12(mu4-hmt)6(mu3-HPO4)(mu2-H2PO4)3(H2PO4)7(H2O)](H3PO4).10.5H2O (11).

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PubMed2000

Bis(&mgr;-hexamethylenetetramine)bis(aquadibromocadmium)diaquadibromo cadmium dihydrate

The title compound, poly[[diaquadibromocadmium-&mgr;-(1,3,5, 7-tetraazatricyclo[3.3.1.1(3, 7)]decane-N(1):N(5))-aquacadmium-di-&mgr;-bromo-aquacadmium-&mgr;-(1, 3,5,7-tetraazatricyclo[3.3.1.1(3, 7)]decane-N(1):N(5))-di-&mgr;-bromo] dihydrate], [Cd(3)Br(6)(C(6)H(12)N(4))(2)(H(2)O)(4)].2H(2)O, is made up of two-dimensional neutral rectangular coordination layers. Each rectangular subunit is enclosed by a pair of Cd(3)(&mgr;(2)-Br)(6)(H(2)O)(3) fragments and a pair of (&mgr;(2)-hmt)Cd(H(2)O)(2)Br(2)(&mgr;(2)-hmt) fragments as sides (hmt is hexamethylenetetramine). The unique Cd(II) atom in the Cd(2)Br(2) ring in the Cd(3)(&mgr;(2)-Br)(6)(H(2)O)(3) fragment is in a slightly distorted octahedral CdNOBr(4) geometry, surrounded by one hmt ligand [2.433 (5) A], one aqua ligand [2.273 (4) A] and four Br atoms [2.6409 (11)-3.0270 (14) A]. The Cd(II) atom in the (&mgr;(2)-hmt)Cd(H(2)O)(2)Br(2)(&mgr;(2)-hmt) fragment lies on an inversion center and is in a highly distorted octahedral CdN(2)O(2)Br(2) geometry, surrounded by two trans-related N atoms of two hmt ligands [2.479 (5) A], two trans-related aqua ligands [2.294 (4) A] and two trans-related Br atoms [2.6755 (12) A]. Adjacent two-dimensional coordination sheets are connected into a three-dimensional network by hydrogen bonds involving lattice water molecules, and the aqua, bromo and hmt ligands belonging to different layers.

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PubMed2000

catena-Poly

In the title complex, [Ag(C(12)H(10)N(2))]NO(3)(n), the Ag atom, which is in a linear AgN(2) geometry, is surrounded by two trans-related N atoms of two bpe ligands [Ag-N = 2.173 (3) and 2.176 (3) A; bpe is trans-1,2-bis(2-pyridyl)ethylene]. The bpe ligands bridge neighbouring Ag atoms to form zigzag polymeric chains in the lattice. These adjacent one-dimensional zigzag chains are extended into a three-dimensional supramolecular array by strong interchain pi.pi interactions between the pyridyl rings of adjacent chains.

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PubMed1999

Self-Assembled Three-Dimensional Coordination Polymers with Unusual Ligand-Unsupported Ag-Ag Bonds: Syntheses, Structures, and Luminescent Properties.

A staggered arrangement like that of the hydrogen atoms in ethane is exhibited by the six phenol groups about each pair of silver atoms in the self-assembled three-dimensional coordination networks [Ag(2)(H(2)L)(3)](n)X(2n) (H(2)L=N,N'-bis(salicylidene)-1,4-diaminobutane; X(-)=NO(3)(-) or ClO(4)(-)); the former is depicted (for clarity the H(2)L ligands are represented by long rods and the Ag atoms by hatched circles). These solids contain short ligand-unsupported metal-metal bonds and display intense blue photoluminescence at room temperature.

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