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Title: Hydrothermal synthesis of new 3d-metal coordination solids with pyridine dicarboxylate, mellitate, arsenate and organothiolate frameworks
Author: Humphrey, S. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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New coordination compounds of 3d-metals with organic or inorganic frameworks prepared by hydrothermal synthesis are reported herein. The solid-state properties such as magnetism and gas porosity of many of these compounds have been studied. Compounds 1-24 have lattices based on pyridine-2,x-carboxylate ligands (x = 3,4 and 5). Of particular interest are the closely related materials [Co3(2,4-pdc)2(μ3-OH)2].9H2O (7a) and [Co3(2,4-pdc)2(μ3-OH)2].7H2O (9) that have 1-dimensional channelled frameworks that retain their porosity when guest solvent is removed. Gas sorption studies of 7a suggest a large capacity for H2 sorption and a high selectivity for that nature of adsorbent. DC susceptibility measurements of the layered bimetallic material [Co3Cu2(2,4-pdc)4(μ3-OH)2(OH2)4] (16) suggest inverse hysteresis-type behaviour. The topological ferrimagnet [Co3(2,5-pdc)2(μ3-OH)2(OH2)2] (18) has been found to exhibit unusual metamagnetism with multiple areas of bistability. The complex inorganic coordination materials 25-27 are based on lattices of AsO4- and exhibit weak ferromagnetic exchange at low temperature. The novel compounds 28-40 are based on lattices of the hexaanion of mellitic acid; the family of compounds M’2[M2(mela)(OH2)2] (M = Mn, Co, Ni; M’ = K, Rb, Cs) (28-31) have been studied by DC magnetometry, while other related structures are also reported. The new materials 41-54 have organothiolate lattices provided by thiosalicylic acid and 2- and 6-mercaptonicotinic. The properties of compounds of MnII formed by in situ redox chemistry and S-S bridge formation (41 and 44) are discussed. Multiple coordination geometries have been observed in the complex materials [Co4(2-mna)(OH2)] (45) and [Fe11(6-mna)8)(μ3-OH)6].H2O (46), while the unusual magnetism of both species is reported. The first example of a thiolate-containing porous coordination solid [Co2(6-mna)2].3H2O (47) is reported and its gas sorption properties have also been studied.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available