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Leroy Cronin

Publications and source records attributed to Leroy Cronin.

32 records · Page 2Linked to original sources
PubMed2004

Synthesis, structure, and complexation of a large 28-mer macrocycle containing two binding sites for either anions or metal ions.

The "one-pot" synthesis and characterization of a large 28-mer macrocycle (H(4)L(2)) with oxamido units capable of complexing guest ions through oxygen or nitrogen donor atoms is reported. Single-crystal structure determination of H(8)L(2)(NO(3))(4) and (Cu(2)[H(2)L(2)](H(2)O)(2))(NO(3))(2) demonstrated that the macrocycle contains two sites capable of complexing two nitrate anions or two copper(II) ions, involving a large structural reorganization in the conformation of the macrocyclic framework on coordination of the copper(II) ions when compared to the nitrate. Electrochemical and magnetic susceptibility measurements on the dinuclear Cu(II) complex and the related mononuclear and trinuclear Cu(II) complexes derived from the related 14-mer macrocycle were carried out and illustrate the role of the oxamido groups in mediating metal-metal interaction and delocalization.

Journal Article↗
PubMed2004

A high-nuclearity "Celtic-ring" isopolyoxotungstate, [H12W36O120]12-, that captures trace potassium ions.

A high-nuclearity {W36} isopolyoxotungstate cluster, [H12W36O120]12-, with a triangular shape has been isolated by using an encapsulating organic cation, protonated triethanolamine. In analogy to an 18-crown-6 crown ether, the cluster captures a potassium ion, present in trace amounts in the reaction system, within its cavity. DFT calculations suggest that the distribution of partial atomic charges over the oxygen framework shows maxima at certain "hotspot" sites, which imply possible routes for further cluster growth based on the {W36} system.

Journal Article↗
PubMed2004

General one-pot, three-step methodology leading to an extended class of N-heterocyclic cations: spontaneous nucleophilic addition, cyclization, and hydride loss.

A new class of phenanthridinium derivative has been isolated from the reaction of 2-bromoethyl-phenanthridinium bromide with a range of primary amines in excellent yields. The reaction pathway is unprecedented and proceeds via three cascade steps: nucleophilic attack of a primary amine on the iminium moiety of a heteroaromatic ring system and cyclization to form a five-membered ring, followed by hydride loss to yield a rearomatized dihydro-1H-imidazo[1,2-f]phenanthridinium derivative. A range of NMR phase transfer experiments were carried out to elucidate the mechanistic pathway, and the methodology has been further developed by means of a biphasic system using N-bromosuccinimide as a co-oxidizing agent. The method has also been extended to other N-heterocyclic cation derivatives such as quinolinium and quinazolinium.

Journal Article↗
PubMed2004

Coordination networks through the dimensions: from discrete clusters to 1D, 2D, and 3D silver(I) coordination polymers with rigid aliphatic amino ligands.

The use of a ligand directed strategy in the assembly of discrete clusters, 1D chains, 2D layers, and 3D networks using aliphatic N-donor ligands has been investigated. The ligands are a family of amines with rigid backbones [cis,cis-1,3,5-triaminocyclohexane (cis-tach), cis,trans-1,3,5-triaminocyclohexane (trans-tach), cis-1,3-diaminocyclohexane (cis-dach), and cis-3,5-diaminopiperidine (cis-dapi)], and their complexation with Ag(I) salts results in a diverse set of architectures with the following compositions: [Ag3(cis-tach)2]F3.4CH(3)OH.0.5H2O (1), [Ag3(cis-tach)2]F3.6H2O (2), ([Ag(cis-dach)]ClO4)n (3), ([Ag(cis-tach)]NO3)n (4), ([Ag(trans-tach)]PF6)n(5), and ([Ag(cis-dapi)]CF3SO3)n (6). Structural analysis shows that compounds 1 and 2 are discrete M(3)L(2) cage-type clusters with varying solvent molecule content. Short Ag...Ag contacts (3.021(8) A) are observed to dimerize discrete units in compound 2. Compound 3 is a 1D zigzag chain formed by coordination to the two primary amines of cis-dach, whereas the tridentate ligands in compounds 4 and 5 (cis-tach and trans-tach, respectively) are able to form tubular architectures by virtue of their ability to "wrap" round the channel walls. An infinite 2D coordination network is demonstrated by compound 6, in which the three coplanar amino donors of cis-dapi coordinate to the trigonal planar Ag(I) ions to form a layered structure of 6(3) topology. These are compared with a previously reported 3D structure, ([Ag(trans-tach)]NO3)n (7), that belongs to this family of architectures.

Journal Article↗
PubMed2003

Polymeric silver(I) coordination tubes.

Isolated polymeric Ag(I) coordination tubes are self-assembled from the rigid triamino ligands cis,cis-1,3,5-triaminocyclohexane (cis-tach) and cis,trans-1,3,5-triaminocyclohexane (trans-tach), forming two topologically equivalent framework motifs.

Journal Article↗
PubMed2003

Controlling dimensionality of silver(I) coordination networks with rigid aliphatic amino ligands: from a 2D to a 3D network of unprecedented topology comprising helical channels.

Ligand-directed 2D and 3D Ag(I) coordination networks are self-assembled from the rigid, topologically related tri-amino ligands cis-3,5-diaminopiperidine (cis-dapi) and cis,trans-1,3,5-triaminocyclohexane (trans-tach), yielding two networks of differing dimensionality including a 3D network of unprecedented topology comprising helical channels.

Journal Article↗
PubMed2003

Synthesis and structure of [Zn(OMe)(L)] x [Zn(OH)(L)] x 2(BPh4), L = cis,cis-1,3,5-tris[(E,E)-3-(2-furyl)acrylideneamino]cyclohexane: structural models of carbonic anhydrase and liver alcohol dehydrogenase.

Direct reaction of [Zn(OH)(L)]+, L = cis,cis-1,3,5-tris[(E,E)-3-(2-furyl)acrylideneamino]cyclohexane, with methanol gives a mixture of the starting material and [Zn(OMe)(L)]+; structural analysis of the complexes shows that they are models of reactive intermediates in the catalytic cycles of the zinc enzymes carbonic anhydrase and liver alcohol dehydrogenase.

Alcohol Dehydrogenase↗