Brian Moulton - Academia.edu (original) (raw)
Papers by Brian Moulton
Molecular Pharmaceutics, 2007
![Research paper thumbnail of Interpenetration of covalent and noncovalent networks in the crystal structures of {[M(4,4′-bipyridine)2(NO3)2]⋅2p-nitroaniline}n where M=Co, 1, Ni, 2, Zn, 3](https://attachments.academia-assets.com/101748879/thumbnails/1.jpg)
](Crystal Engineering, 2001
The synthesis and crystal structures of {[M(4,4Ј-bipyridine) 2 (NO 3) 2 ]•2p-nitroaniline} n , M=... more The synthesis and crystal structures of {[M(4,4Ј-bipyridine) 2 (NO 3) 2 ]•2p-nitroaniline} n , M=Co, 1, Ni, 2, Zn, 3, are described. 1, 2 and 3 crystallize in the form of compounds that can be described as interpenetrating covalent and noncovalent networks. Analysis of the crystal packing in these compounds reveals that the p-nitroaniline molecules form a noncovalent network that is complementary from a topological perspective with [M(4,4Ј-bipyridine) 2 (NO 3) 2 ] networks, which exist as square grids. These structures are interpreted in the broader perspective of crystal engineering strategies and development of new hybrid materials.
Crystal Engineering: From Molecules and Crystals to Materials, 1999
Solids that crystallize in acentric space groups are predisposed to exhibit useful bulk physical ... more Solids that crystallize in acentric space groups are predisposed to exhibit useful bulk physical properties in the context of new materials for electrooptical applications’, especially devices based upon second-order nonlinear optic (NLO), piezoelectric, pyroelectric or ferroelectric activity. It should therefore be unsurprising that the pursuit of new classes of acentric, or polar, solids has been ongoing for many years. Although a crystallographic center of inversion can be precluded by building materials from homochiral components, there are two significant limitations: (1) requirements for homochiral starting materials and/or products are significant hurdles for synthetic chemists; (2) the use of homochiral building blocks does not in any way ensure optimum alignment of dipoles. The potential importance of new design strategies that are independent of the need for chiral building blocks should therefore be apparent.
![Research paper thumbnail of Interpenetrating covalent and noncovalent nets in the crystal structures of [M(4,4′-bipyridine)2(NO3)2]·3C10H8 (M = Co, Ni)](https://attachments.academia-assets.com/101748878/thumbnails/1.jpg)
](Crystal Engineering, 1999
The synthesis and crystal structures of [M(4,4Ј-bipyridine) 2 (NO 3) 2 ]⅐3naphthalene (M ϭ Co, 1⅐... more The synthesis and crystal structures of [M(4,4Ј-bipyridine) 2 (NO 3) 2 ]⅐3naphthalene (M ϭ Co, 1⅐3naphthalene; Ni, 2⅐3naphthalene) are reported. 1⅐3naphthalene and 2⅐3naphthalene are isostructural and represent rare examples of interpenetrating planar networks that are chemically and topologically different. It appears that the networks coexist because the (4,4) topology of the cobalt and nickel square grids is complementary to the (6,3) topology of the naphthalene honeycomb network, resulting in an inclined interpenetrated 3D architecture. This observation is discussed in the context of rational design strategies for hybrid solids.
European Journal of Inorganic Chemistry, 2014
Three new tetranuclear complexes [MnIII2CoIII2O2(L)2][ClO4]2 (1), [MnIII2FeIII2O2(L)2][ClO4]2 (2)... more Three new tetranuclear complexes [MnIII2CoIII2O2(L)2][ClO4]2 (1), [MnIII2FeIII2O2(L)2][ClO4]2 (2), and [MnIII2MnIII2O2(L)2][MnII(NCS)4] (3) have been synthesized through reactions of the mononuclear [MnIIIL] precursor with the corresponding metal perchlorate under aerobic conditions [H3L = tris(2-salicylaldimine)amine, a condensation product between tris(2-aminoethyl)amine and salicylaldehyde in a 1:3 molar ratio]. These compounds have been characterized by spectroscopic and analytical techniques including single-crystal X-ray structure analysis, electron paramagnetic resonance (EPR) spectroscopy, Mossbauer spectroscopy, and magnetic measurements. The structure of 1 consists of oxo-/phenoxo-bridged CoIII and MnIII centers in a defective double-cubane topology. The molecules of 2 and 3 have similar structures with the CoIII centers changed to FeIII centers in 2 and to MnIII centers in 3. These isostructural complexes have been scrutinized with regard to changes in distortions (distances and angles) of the metal coordination spheres. Magnetic studies indicate that 1, 2, and 3 show predominant antiferromagnetic interactions. Changes in the electronic properties concomitant with changes in the distortions in 1, 2, and 3 are analyzed in terms of magnetostructural correlations.
This work endeavors to delineate modern paradigms for crystal engineering, i.e. the design and su... more This work endeavors to delineate modern paradigms for crystal engineering, i.e. the design and supramolecular synthesis of functional molecular materials. Paradigms predicated on an understanding of the geometry of polygons and polyhedra are developed. The primary focus is on structural determination by single crystal x-ray crystallography, structural interpretation using a suite of graphical visualization and molecular modeling software, and on the importance of proper graphical representation in the presentation and explanation of crystal structures. A detailed analysis of a selected series of crystal structures is presented. The reduction of these molecular networks to schematic representations that illustrate their fundamental connectivity facilitates the understanding of otherwise complex supramolecular solids. Circuit symbols and Schlafli notation are used to describe the network topologies, which enables networks of different composition and metrics to be easily compared. Thi...
Organic Letters, 2001
Intramolecular C−H insertion reaction of r-diazo-r-(phenylsulfonyl)acetamides proceeded with high... more Intramolecular C−H insertion reaction of r-diazo-r-(phenylsulfonyl)acetamides proceeded with high regio-and stereoselectivities to afford highly functionalized γ-lactams predominantly or exclusively. The high regioselectivity was attributed to the use of the phenylsulfonyl moiety, which altered electron density at the carbenoid center and exerted a steric effect during the insertion reaction. Also described herein are three control elements to determine regioselectivity, which are amide conformational, stereoelectronic, and substituent effects.
Journal of the American Chemical Society, 2003
Supporting Information for MS# JA035776P "Crystal Engineering of Novel Co-Crystals of a Triazole ... more Supporting Information for MS# JA035776P "Crystal Engineering of Novel Co-Crystals of a Triazole Drug with 1,4-Dicarboxylic Acids" PXRD patterns from 2-40 degrees-2-theta for 2a-2f 2a (TPI-315) 2 (fumaric acid) 800 600
Journal of Applied Physics, 2003
Magnetic studies of dimeric copper complexes reveal interesting and predictable cooperative respo... more Magnetic studies of dimeric copper complexes reveal interesting and predictable cooperative responses governed by the underlying topological lattice configurations. Temperature dependent susceptibility in several compounds measured with a physical property measurement system indicates predominantly antiferromagnetic exchange coupling. Both intra- and interdimer interactions are found to be important and the data could be fit well with a modified Bleaney-Bowers model from
Inorganic Chemistry, 2008
The employment of the anion of 2,6-diacetylpyridine dioxime (dapdoH 2) as a pentadentate chelate ... more The employment of the anion of 2,6-diacetylpyridine dioxime (dapdoH 2) as a pentadentate chelate in transition metal cluster chemistry is reported. The syntheses, crystal structures, and magnetochemical characterization are described for [Mn 6 O 2 (OMe) 2 (dapdo) 2 (dapdoH) 4 ](ClO 4) 2 (1), [Mn 6 O 2 (OMe) 2 (dapdo) 2 (dapdoH) 4 ][Ca(NO 3) 4 ] (2), and [Mn 8 O 4 (OH) 4 (OMe) 2 (N 3) 2 (dapdo) 2 (dapdoH) 2 (H 2 O) 2 ] (3). The reaction of [Mn 3 O(O 2 CMe) 6 (py) 3 ](ClO 4) with 3 equiv of dapdoH 2 (with or without 2 equiv of NEt 3) in MeOH gave 1. The same cation, but with a [Ca(NO 3) 4 ] 2anion, was found in complex 2, which was obtained from the reaction in MeOH between Mn(NO 3) 2 , Ca(NO 3) 2 , and dapdoH 2 in the presence of NEt 3. In contrast, addition of NaN 3 to several reactions comprising MnCl 2 , dapdoH 2 , and NEt 3 in MeOH gave the octanuclear complex 3. Complexes 1−3 all possess rare topologies and are mixed-valence: 2Mn II , 4Mn III for 1 and 2, and 2Mn II , 6Mn III for 3. The core of the cation of 1 and 2 consists of two edge-sharing Mn 4 tetrahedra at the center of each of which is a µ 4-O 2ion. Peripheral ligation is provided by two µ-OMe-, four µ-dapdoH-, and two µ 3-dapdo 2groups. The core of 3 consists of two [Mn II Mn III 3 (µ 3-O) 2 ] 7+ "butterfly" units linked together by one of the µ 3-O 2ions, which thus becomes µ 4. Peripheral ligation is provided by four µ-OMe-, two µ-OH-, two µ-dapdoH-, and two µ 4-dapdo 2groups. Variable-temperature, solid-state dc and ac magnetization studies were carried out on complexes 1−3 in the 5.0−300 K range; the data for 1 and 2 are identical. Fitting of the obtained magnetization versus field (H) and temperature (T) data by matrix diagonalization and including only axial anisotropy (zero-field splitting, D) established that 1 possesses an S) 5 ground state with D) −0.24 cm-1. For 3, low-lying excited states precluded obtaining a good fit from the magnetization data, and the ground state was instead determined from the ac data, which indicated an S) 1 ground state for 3. The combined work demonstrates the ligating flexibility of pyridyl-dioxime chelates and their usefulness in the synthesis of new polynuclear Mn x clusters without requiring the co-presence of carboxylate ligands.
Crystal Growth & Design, 2006
An unprecedented (8,3)-a 3D coordination network was synthesized using crystal engineering strate... more An unprecedented (8,3)-a 3D coordination network was synthesized using crystal engineering strategies as one of three concomitant supramolecular isomers of the general formula [Cu 2 (tae)(bipy) 2 ]‚2NO 3-‚xS (bipy) 4,4′-bipyridine; tae) dibasic tetraacetylethane; S) solvent: H 2 O/MeOH). The (8,3)-a network yields optically active single crystals with 58% solvent-accessible volume, despite 4-fold interpenetration.
Crystal Growth & Design, 2007
A series of crystalline mixed-ligand copper(II)-aspirinate coordination complexes have been synth... more A series of crystalline mixed-ligand copper(II)-aspirinate coordination complexes have been synthesized, structurally characterized, and shown to exhibit a diverse range of pharmacologically relevant properties, such as bulk solubility, solubility ratio (S wo / S ow), and partition coefficient.
[
Chemical Communications, 1999
... Kumar Biradha, Konstantin V. Domasevitch, Brian Moulton, Corey Seward and Michael J. Zaworotk... more ... Kumar Biradha, Konstantin V. Domasevitch, Brian Moulton, Corey Seward and Michael J. Zaworotko* Department of Chemistry, The University of Winnipeg, Winnipeg, Manitoba, R3B 2E9, Canada. ... 4 LR MacGillivray, RH Groeneman and JL Atwood, J. Am. Chem. ...
Chemical Communications, 2007
Molecular Pharmaceutics, 2007
Crystal Engineering, 2001
The synthesis and crystal structures of {[M(4,4Ј-bipyridine) 2 (NO 3) 2 ]•2p-nitroaniline} n , M=... more The synthesis and crystal structures of {[M(4,4Ј-bipyridine) 2 (NO 3) 2 ]•2p-nitroaniline} n , M=Co, 1, Ni, 2, Zn, 3, are described. 1, 2 and 3 crystallize in the form of compounds that can be described as interpenetrating covalent and noncovalent networks. Analysis of the crystal packing in these compounds reveals that the p-nitroaniline molecules form a noncovalent network that is complementary from a topological perspective with [M(4,4Ј-bipyridine) 2 (NO 3) 2 ] networks, which exist as square grids. These structures are interpreted in the broader perspective of crystal engineering strategies and development of new hybrid materials.
Crystal Engineering: From Molecules and Crystals to Materials, 1999
Solids that crystallize in acentric space groups are predisposed to exhibit useful bulk physical ... more Solids that crystallize in acentric space groups are predisposed to exhibit useful bulk physical properties in the context of new materials for electrooptical applications’, especially devices based upon second-order nonlinear optic (NLO), piezoelectric, pyroelectric or ferroelectric activity. It should therefore be unsurprising that the pursuit of new classes of acentric, or polar, solids has been ongoing for many years. Although a crystallographic center of inversion can be precluded by building materials from homochiral components, there are two significant limitations: (1) requirements for homochiral starting materials and/or products are significant hurdles for synthetic chemists; (2) the use of homochiral building blocks does not in any way ensure optimum alignment of dipoles. The potential importance of new design strategies that are independent of the need for chiral building blocks should therefore be apparent.
Crystal Engineering, 1999
The synthesis and crystal structures of [M(4,4Ј-bipyridine) 2 (NO 3) 2 ]⅐3naphthalene (M ϭ Co, 1⅐... more The synthesis and crystal structures of [M(4,4Ј-bipyridine) 2 (NO 3) 2 ]⅐3naphthalene (M ϭ Co, 1⅐3naphthalene; Ni, 2⅐3naphthalene) are reported. 1⅐3naphthalene and 2⅐3naphthalene are isostructural and represent rare examples of interpenetrating planar networks that are chemically and topologically different. It appears that the networks coexist because the (4,4) topology of the cobalt and nickel square grids is complementary to the (6,3) topology of the naphthalene honeycomb network, resulting in an inclined interpenetrated 3D architecture. This observation is discussed in the context of rational design strategies for hybrid solids.
European Journal of Inorganic Chemistry, 2014
Three new tetranuclear complexes [MnIII2CoIII2O2(L)2][ClO4]2 (1), [MnIII2FeIII2O2(L)2][ClO4]2 (2)... more Three new tetranuclear complexes [MnIII2CoIII2O2(L)2][ClO4]2 (1), [MnIII2FeIII2O2(L)2][ClO4]2 (2), and [MnIII2MnIII2O2(L)2][MnII(NCS)4] (3) have been synthesized through reactions of the mononuclear [MnIIIL] precursor with the corresponding metal perchlorate under aerobic conditions [H3L = tris(2-salicylaldimine)amine, a condensation product between tris(2-aminoethyl)amine and salicylaldehyde in a 1:3 molar ratio]. These compounds have been characterized by spectroscopic and analytical techniques including single-crystal X-ray structure analysis, electron paramagnetic resonance (EPR) spectroscopy, Mossbauer spectroscopy, and magnetic measurements. The structure of 1 consists of oxo-/phenoxo-bridged CoIII and MnIII centers in a defective double-cubane topology. The molecules of 2 and 3 have similar structures with the CoIII centers changed to FeIII centers in 2 and to MnIII centers in 3. These isostructural complexes have been scrutinized with regard to changes in distortions (distances and angles) of the metal coordination spheres. Magnetic studies indicate that 1, 2, and 3 show predominant antiferromagnetic interactions. Changes in the electronic properties concomitant with changes in the distortions in 1, 2, and 3 are analyzed in terms of magnetostructural correlations.
This work endeavors to delineate modern paradigms for crystal engineering, i.e. the design and su... more This work endeavors to delineate modern paradigms for crystal engineering, i.e. the design and supramolecular synthesis of functional molecular materials. Paradigms predicated on an understanding of the geometry of polygons and polyhedra are developed. The primary focus is on structural determination by single crystal x-ray crystallography, structural interpretation using a suite of graphical visualization and molecular modeling software, and on the importance of proper graphical representation in the presentation and explanation of crystal structures. A detailed analysis of a selected series of crystal structures is presented. The reduction of these molecular networks to schematic representations that illustrate their fundamental connectivity facilitates the understanding of otherwise complex supramolecular solids. Circuit symbols and Schlafli notation are used to describe the network topologies, which enables networks of different composition and metrics to be easily compared. Thi...
Organic Letters, 2001
Intramolecular C−H insertion reaction of r-diazo-r-(phenylsulfonyl)acetamides proceeded with high... more Intramolecular C−H insertion reaction of r-diazo-r-(phenylsulfonyl)acetamides proceeded with high regio-and stereoselectivities to afford highly functionalized γ-lactams predominantly or exclusively. The high regioselectivity was attributed to the use of the phenylsulfonyl moiety, which altered electron density at the carbenoid center and exerted a steric effect during the insertion reaction. Also described herein are three control elements to determine regioselectivity, which are amide conformational, stereoelectronic, and substituent effects.
Journal of the American Chemical Society, 2003
Supporting Information for MS# JA035776P "Crystal Engineering of Novel Co-Crystals of a Triazole ... more Supporting Information for MS# JA035776P "Crystal Engineering of Novel Co-Crystals of a Triazole Drug with 1,4-Dicarboxylic Acids" PXRD patterns from 2-40 degrees-2-theta for 2a-2f 2a (TPI-315) 2 (fumaric acid) 800 600
Journal of Applied Physics, 2003
Magnetic studies of dimeric copper complexes reveal interesting and predictable cooperative respo... more Magnetic studies of dimeric copper complexes reveal interesting and predictable cooperative responses governed by the underlying topological lattice configurations. Temperature dependent susceptibility in several compounds measured with a physical property measurement system indicates predominantly antiferromagnetic exchange coupling. Both intra- and interdimer interactions are found to be important and the data could be fit well with a modified Bleaney-Bowers model from
Inorganic Chemistry, 2008
The employment of the anion of 2,6-diacetylpyridine dioxime (dapdoH 2) as a pentadentate chelate ... more The employment of the anion of 2,6-diacetylpyridine dioxime (dapdoH 2) as a pentadentate chelate in transition metal cluster chemistry is reported. The syntheses, crystal structures, and magnetochemical characterization are described for [Mn 6 O 2 (OMe) 2 (dapdo) 2 (dapdoH) 4 ](ClO 4) 2 (1), [Mn 6 O 2 (OMe) 2 (dapdo) 2 (dapdoH) 4 ][Ca(NO 3) 4 ] (2), and [Mn 8 O 4 (OH) 4 (OMe) 2 (N 3) 2 (dapdo) 2 (dapdoH) 2 (H 2 O) 2 ] (3). The reaction of [Mn 3 O(O 2 CMe) 6 (py) 3 ](ClO 4) with 3 equiv of dapdoH 2 (with or without 2 equiv of NEt 3) in MeOH gave 1. The same cation, but with a [Ca(NO 3) 4 ] 2anion, was found in complex 2, which was obtained from the reaction in MeOH between Mn(NO 3) 2 , Ca(NO 3) 2 , and dapdoH 2 in the presence of NEt 3. In contrast, addition of NaN 3 to several reactions comprising MnCl 2 , dapdoH 2 , and NEt 3 in MeOH gave the octanuclear complex 3. Complexes 1−3 all possess rare topologies and are mixed-valence: 2Mn II , 4Mn III for 1 and 2, and 2Mn II , 6Mn III for 3. The core of the cation of 1 and 2 consists of two edge-sharing Mn 4 tetrahedra at the center of each of which is a µ 4-O 2ion. Peripheral ligation is provided by two µ-OMe-, four µ-dapdoH-, and two µ 3-dapdo 2groups. The core of 3 consists of two [Mn II Mn III 3 (µ 3-O) 2 ] 7+ "butterfly" units linked together by one of the µ 3-O 2ions, which thus becomes µ 4. Peripheral ligation is provided by four µ-OMe-, two µ-OH-, two µ-dapdoH-, and two µ 4-dapdo 2groups. Variable-temperature, solid-state dc and ac magnetization studies were carried out on complexes 1−3 in the 5.0−300 K range; the data for 1 and 2 are identical. Fitting of the obtained magnetization versus field (H) and temperature (T) data by matrix diagonalization and including only axial anisotropy (zero-field splitting, D) established that 1 possesses an S) 5 ground state with D) −0.24 cm-1. For 3, low-lying excited states precluded obtaining a good fit from the magnetization data, and the ground state was instead determined from the ac data, which indicated an S) 1 ground state for 3. The combined work demonstrates the ligating flexibility of pyridyl-dioxime chelates and their usefulness in the synthesis of new polynuclear Mn x clusters without requiring the co-presence of carboxylate ligands.
Crystal Growth & Design, 2006
An unprecedented (8,3)-a 3D coordination network was synthesized using crystal engineering strate... more An unprecedented (8,3)-a 3D coordination network was synthesized using crystal engineering strategies as one of three concomitant supramolecular isomers of the general formula [Cu 2 (tae)(bipy) 2 ]‚2NO 3-‚xS (bipy) 4,4′-bipyridine; tae) dibasic tetraacetylethane; S) solvent: H 2 O/MeOH). The (8,3)-a network yields optically active single crystals with 58% solvent-accessible volume, despite 4-fold interpenetration.
Crystal Growth & Design, 2007
A series of crystalline mixed-ligand copper(II)-aspirinate coordination complexes have been synth... more A series of crystalline mixed-ligand copper(II)-aspirinate coordination complexes have been synthesized, structurally characterized, and shown to exhibit a diverse range of pharmacologically relevant properties, such as bulk solubility, solubility ratio (S wo / S ow), and partition coefficient.
[
Chemical Communications, 1999
... Kumar Biradha, Konstantin V. Domasevitch, Brian Moulton, Corey Seward and Michael J. Zaworotk... more ... Kumar Biradha, Konstantin V. Domasevitch, Brian Moulton, Corey Seward and Michael J. Zaworotko* Department of Chemistry, The University of Winnipeg, Winnipeg, Manitoba, R3B 2E9, Canada. ... 4 LR MacGillivray, RH Groeneman and JL Atwood, J. Am. Chem. ...
Chemical Communications, 2007