The Crystal and Molecular Structure of Pteridine with Additional Paper on the Structure of Cellulose Fibres

Hamor, Thomas A (1956) The Crystal and Molecular Structure of Pteridine with Additional Paper on the Structure of Cellulose Fibres. PhD thesis, University of Glasgow.

Abstract

The main part of the work described in this thesis is concerned with the determination of the crystal and molecular structure of pteridine by X-ray crystallographic methods. The unit cell dimensions and space group of 'substance P', a dipteridyl derivative of unknown structure were also obtained. An additional paper deals with an investigation of the structure of the cellulose fibre sisal with the electron microscope. Pteridine crystallises in the orthorhombic non-centrosymmetrical space group Pna2 1 (C9 2v), molecules per unit cell. The unit cell dimensions are a = 24.70, b = 3.79, c = 6.32 A. The crystal and molecular structure has been determined with coordinate standard deviations of about 0.03 A from a study of Fourier and Fourier difference syntheses projecting on (010) and (001). The molecule is planar to within 0.06 A and the bond lengths vary between 1.28 and 1.41 A for carbon-nitrogen bonds and between 1.35 and 1.42 A for carbon-carbon bonds. The experimental bond length measurements are compared with molecular orbital calculations and are found to agree to within the limits of the experimental errors. The investigation was hampered by the fact that owing to the nature of the crystals only less than half of the possible reflections could be observed with CuKa radiation. Additional difficulties were caused by the non-centrosymmetrical nature of the one projection which gives good resolution and also by the difficulty of distinguishing between carbon and nitrogen atoms. The peak heights in the final electron density projection on (010) confirm the position of the nitrogen atoms, and the hydrogen atoms are also resolved. The crystals of 'substance P' dihydrochloride dihydrate are monoclinic, space group 1a (C 4s), with four molecules per unit cell. The unit cell dimensions are a = 12.12, b = 11.21, c = 13.46 A; beta= 114

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Physical chemistry, Molecular chemistry, Organic chemistry
• Date of Award: 1956
• Depositing User: Enlighten Team
• Unique ID: glathesis:1956-79206
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Mar 2020 11:28
• Last Modified: 05 Mar 2020 11:28
• URI: https://theses.gla.ac.uk/id/eprint/79206