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Title: Structures and properties of multifunctional molecular materials : combining chirality and conductivity
Author: Lopez, Jordan R.
ISNI:       0000 0004 7959 9350
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2017
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The objective of this thesis is to investigate the influence of chirality upon conducting materials through the synthesis of charge-transfer salts by diffusion or electrocrystallisation of enantiopure/racemic donor molecules and anions. This thesis presents the characterisation of new charge-transfer salts from two new donor molecules: BHM-EDT-TTF and BHM-BEDT-TTF. BHM-EDT-TTF has produced a family of 1:1 semiconductors with tetrahedral and octahedral anions BF4, ClO4 and PF6. The room temperature resistivities and activation energies are similar for all enantiopure salts but slightly different for their racemic/meso forms. The racemic donor BHM-BEDT-TTF forms a semiconducting 2:1 salt with chloride, and an insulating 1:1 salt with TCNQ which has an interesting packing arrangement in that the donors are segregated into stacks consisting of only a single enantiomer in the mode SS:SS:RR:RR:SS:SS. The first charge-transfer salts have been synthesised and characterised from BEDT-TTF with racemic spiroboronate anions. Five salts of BEDT-TTF with either B(malate)2, B(mandelate)2, or B(glycolate)2 show a variety of novel packing arrangements and conducting properties. These salts are also the first examples of preferential diastereomeric induction within the electrocrystallisation environment. Using spiroboronate anions with enantiopure ligands has also produced crystals having a macromolecular helical morphology. The first examples of charge-transfer salts containing racemic and chiral lanthanide anions are reported including the spontaneous resolution of the racemic [Gd(dipicolinato)3]3- anion in the presence of BEDT-TTF and bromobenzene to produce a chiral, paramagnetic, semiconductor. A new molecular superconductor, β"-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3].18-crown-6, has been synthesised. This is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β"). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system strongly suggests that the superconducting transition is a Kosterlitz-Thouless transition.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available