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Coventry, United Kingdom

Smith G.,Queensland University of Technology | Lynch D.E.,Exilica Ltd
Acta Crystallographica Section C: Structural Chemistry | Year: 2016

The morpholinium (tetrahydro-2H-1,4-oxazin-4-ium) cation has been used as a counter-ion in both inorganic and organic salt formation and particularly in metal complex stabilization. To examine the influence of interactive substituent groups in the aromatic rings of benzoic acids upon secondary structure generation, the anhydrous salts of morpholine with salicylic acid, C4H10NO+ C7H5O3 -, (I), 3,5-dinitrosalicylic acid, C4H10NO+ C7H3N2O7 -, (II), 3,5-dinitrobenzoic acid, C4H10NO+ C7H3N2O6 -, (III), and 4-nitroanthranilic acid, C4H10NO+ C7H5N2O4 -, (IV), have been prepared and their hydrogen-bonded crystal structures are described. In the crystal structures of (I), (III) and (IV), the cations and anions are linked by moderately strong N - H⋯Ocarboxyl hydrogen bonds, but the secondary structure propagation differs among the three, viz. one-dimensional chains extending along [010] in (I), a discrete cyclic heterotetramer in (III), and in (IV), a heterotetramer with amine N - H⋯O hydrogen-bond extensions along b, giving a two-layered ribbon structure. With the heterotetramers in both (III) and (IV), the ion pairs are linked though inversion-related N - H⋯Ocarboxylate hydrogen bonds, giving cyclic R 4 4(12) motifs. With (II), in which the anion is a phenolate rather than a carboxylate, the stronger assocation is through a symmetric lateral three-centre cyclic R 1 2(6) N - H⋯(O,O′) hydrogen-bonding linkage involving the phenolate and nitro O-atom acceptors of the anion, with extension through a weaker O - H⋯Ocarboxyl hydrogen bond. This results in a one-dimensional chain structure extending along [100]. In the structures of two of the salts [i.e. (II) and (IV)], there are also π-π ring interactions, with ring-centroid separations of 3.5516 (9) and 3.7700 (9) A in (II), and 3.7340 (9) A in (IV). © 2016 International Union of Crystallography.

Smith G.,Queensland University of Technology | Lynch D.E.,Exilica Ltd
Acta Crystallographica Section E: Crystallographic Communications | Year: 2015

The anhydrous salts of 2-(1H-indol-3-yl)ethanamine (tryptamine) with isomeric (2,4-dichlorophenoxy)acetic acid (2,4-D) and (3,5-dichlorophenoxy)acetic (3,5-D), both C10H13N2 +·C8H5Cl2O3 - [(I) and (II), respectively], have been determined and their one-dimensional hydrogen-bonded polymeric structures are described. In the crystal of (I), the aminium H atoms are involved in three separate inter-species N-H⋯O hydrogen-bonding interactions, two with carboxylate O-atom acceptors and the third in an asymmetric three-centre bidentate carboxylate O,O' chelate [graph set R1 2 (4)]. The indole H atom forms an N-H·Ocarboxylate hydrogen bond, extending the chain structure along the b-axis direction. In (II), two of the three aminium H atoms are also involved in N-HOcarboxylate hydrogen bonds similar to (I) but with the third, a threecentre asymmetric interaction with carboxylate and phenoxy O atoms is found [graph set R1 2 (5)]. The chain polymeric extension is also along b. There are no π - π ring interactions in either of the structures. The aminium side-chain conformations differ significantly between the two structures, reflecting the conformational ambivalence of the tryptaminium cation, as found also in the benzoate salts.

Mume E.,Australian Nuclear Science and Technology Organisation | Mume E.,Australian National University | Lynch D.E.,Exilica Ltd | Uedono A.,University of Tsukuba | Smith S.V.,Australian Nuclear Science and Technology Organisation
Dalton Transactions | Year: 2011

Understanding how the size, charge and number of available pores in porous material influences the uptake and release properties is important for optimising their design and ultimately their application. Unfortunately there are no standard methods for screening porous materials in solution and therefore formulations must be developed for each encapsulated agent. This study investigates the potential of a library of radiotracers (nuclear sensors) for assessing the binding properties of hollow silica shell materials. Uptake and release of Cu2+ and Co2+ and their respective complexes with polyazacarboxylate macrocycles (dota and teta) and a series of hexa aza cages (diamsar, sarar and bis-(p-aminobenzyl)-diamsar) from the hollow silica shells was monitored using their radioisotopic analogues. Coordination chemistry of the metal (M) species, subtle alterations in the molecular architecture of ligands (Ligand) and their resultant complexes (M-Ligand) were found to significantly influence their uptake over pH 3 to 9 at room temperature. Positively charged species were selectively and rapidly (within 10 min) absorbed at pH 7 to 9. Negatively charged species were preferentially absorbed at low pH (3 to 5). Rates of release varied for each nuclear sensor, and time to establish equilibrium varied from minutes to days. The subtle changes in design of the nuclear sensors proved to be a valuable tool for determining the binding properties of porous materials. The data support the development of a library of nuclear sensors for screening porous materials for use in optimising the design of porous materials and the potential of nuclear sensors for high through-put screening of materials. © 2011 The Royal Society of Chemistry.

Smith G.,Queensland University of Technology | Lynch D.E.,Exilica Ltd
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2013

The crystal structures of the anhydrous products from the interaction of 5-(4-bromophenyl)-1,3,4-thiadiazol-2-amine with 2-(naphthalen-2-yloxy)acetic acid, viz. the 1:1 adduct C8H6BrN3S· C12H10O3, (I), and with 3,5-dinitrobenzoic acid, viz. the salt 2-amino-5-(4-bromophenyl)-1,2,4-thiadiazol-3-ium 3,5-dinitrobenzoate, C8H7BrN3S +·C7H3N2O6 -, (II), have been determined. In adduct (I), a heterodimer is formed through a cyclic hydrogen-bonding motif [graph set R2 2(8)], involving carboxylic acid-heteroatom O - H⋯N and amine-carboxylic acid N - H⋯O interactions. The heterodimers are essentially planar, with a thiadiazole-to-naphthalene ring dihedral angle of 15.9 (2)° and an intramolecular thiadiazole-to-benzene ring angle of 4.7 (2)°. An amine-heteroatom N - H⋯N hydrogen bond between the heterodimers generates a one-dimensional chain structure extending down [001]. Also present are weak benzene-benzene and naphthalene-naphthalene π-π stacking interactions down the b axis [minimum ring-centroid separation = 3.936 (3) Å]. With salt (II), the cation-anion association is also through a cyclic R2 2(8) motif but involving duplex N - H⋯Ocarboxylate hydrogen bonds, giving a heterodimer that is close to planar [dihedral angles between the thiadiazole ring and the two benzene rings = 5.00 (16) (intra) and 7.23 (15)° (inter)]. A secondary centrosymmetric cyclic (8) N - H⋯Ocarboxylate hydrogen-bonding association involving the second amino H atom generates a heterotetramer. Also present in the crystal structure are weak π-π interactions between thiadiazolium rings [minimum ring-centroid separation = 3.9466 (18) Å], as well as a short Br⋯Onitro interaction [3.314 (4) Å]. The two structures reported here now provide a total of three crystallographically characterized examples of cocrystalline products from the interaction of 5-(4-bromophenyl)-1,3,4- thiadiazol-2-amine with carboxylic acids, of which only one involves proton transfer. © 2013 International Union of Crystallography.

Lynch D.E.,Exilica Ltd
Metals | Year: 2015

Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry. © 2015, by the authors.

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