http://kristiankjaer.dk/krkj/Some_Publications/Principles_GIXD_n_Monolayers_Air-Water__PhysRep_vol_246_p_251-313_1994.pdf

Principles and applications of grazing incidence X-ray and neutron scattering from ordered molecular monolayers at the air-water interface

Mass spectrometry in lipid research.

CHAPTER 8 – The Distribution of Alkanes

Cellulose as a material has been widely used for centuries in all kinds of practical applications. However, its chemical composition, structure and morphology were also unknown for centuries. The modern history of cellulose chemistry actually began in 1837 when Anselme Payen chemically identified cellulose from plants. Since then, the establishment of its chemical and physical structures has undergone multitudinous periods of struggle. Until the early 1920s, many scientists believed that cellulose was made up of a few small molecules of glucose or cellobiose. Very few scientists accepted the premiss that it was a polymer. The controversial debates were continued for over ten years. Eventually, substantial experimental data provided proof that cellulose is a covalently linked, high-molecular-weight macromolecule. This fact also provided the foundation for the establishment of polymer science. Some of the historical development of chemistry and structures are briefly reviewed, and recent approaches to studying cellulose structures with new instrumentation are discussed.

Cellulose: a random walk along its historical path

The methyl-branched fortifications of Mycobacterium tuberculosis.

INVESTIGATIONS using a thermostated double-acting recording surface balance of the Wilhelmy-Dervichian type1,2 reveal an interesting series of phase changes in condensed monolayers of normal chain fatty acids of high molecular weight As an example, we may take the surface pressure – area curves for n-docosanoic (behenic) acid3 spread on acid (0·01 N hydrochloric acid) substrate shown in Fig 1 At the lowest temperature the solid film gives a smooth pressure – area curve and the area can be reduced down to about 18·6 sq A per molecule before a gradual collapse sets in At this area the chains are evidently vertical and as closely packed as in the normal three-dimensional hydrocarbon crystal, in which the cross-section of the chains is about 18·4 sq A This close-packed solid phase may be denoted by CS When the temperature is raised, another phase, L2, appears5, the stability range of which increases with temperature At 8·2° a new phase, which we may call L'2, appears and is quite marked in the curve for 10° in Fig 1 At 13·8° the high-pressure phase S appears and the curve for 14·8° shows a transition S r CS which is rapidly displaced towards higher pressures with raising temperature Above 18°, CS has disappeared and S shows a sharp collapse at about 55 dynes pressure The smallest area at which the phase S is stable is about 19·3 sq A It seems likely, therefore, that the molecules are vertical and perform strong torsional oscillations6 or complete rotations, as the area per chain corresponds to that found in hydrocarbon crystals near the melting point4 (A few degrees below the melting point some hydrocarbons show a gradual, others an abrupt, change from a state of lower symmetry into one of hexagonal symmetry, in which the vertical chains are rotating about the long axis)

Phase Transitions in Condensed Monolayers of Normal Chain Carboxylic Acids

/pdf/synthesis-of-methyl-2d-4d-6d-trimethylnonacosanoate-and-1fwzqtnc6y.pdf

Synthesis of (--)-Methyl 2D,4D,6D-Trimethylnonacosanoate and Identification of C32-Mycocerosic Acid as a 2,4,6,8-Tetramethyloctacosanoic Acid.

The surface chemistry studies carried out in our laboratory can be traced back to the Department of Colloid Science in Cambridge, England, where one of the present authors spent a year as a student just thirty years ago, working with Prof. (now Sir) E. K. Rideal and Dr. J. H. Sehulman. The original aim was to explore the possibilities of the monolayer technique in the elucidation of the structure of some complex lipid molecules of bacterial origin, viz., phthiocerol (1), the so-called phthioic acid (2), and certain other fatty acids (3). These structure problems were later solved by mass spectrometry (cf. 4) but the monolayer work led to the discovery of new phases in condensed monolayers (5, 6), and the use of the surface phase diagram for the deterruination of the composition of mixtures of fatty acids was demonstrated (7). The relation between the different "twodimensional" monolayerphases observed and the arrangement of the molecules in the three-dimensional crystal has been the subjeer of discussion (8-10). These problems have been studied in our laboratory in recent years (11). Detailed monolayer studies together with X-ray crystal structure studies have now led to a fairly complete correlation between monolayer states and three-dimensional crystalline arrangements of long-chain molecules. The extension of previous X-ray single crystal structure studies of glycerides carried out in this laboratory (12) to glyceridewater systems (13) has given new infermarion about the phase behavior of such systems. The newly developed electron spectroscopy of nonbinding electrons in the inner shells (14) has recently been applied to Langmuir-Blodgett multi]ayers (15). It seems likely that this technique will become a very important tool in studies of surface layers.

Some recent studies on the structural arrangements of lipids in surface layers and interphases.

/pdf/the-qualitative-separation-of-purines-pyrimidines-and-7x5ww65mj4.pdf

The Qualitative Separation of Purines, Pyrimidines, and Nucleosides by Paper Chromatography.

/pdf/very-long-hydrocarbon-chains-i-the-synthesis-of-n-52cckncpn8.pdf

Stina Ställberg-Stenhagen

Papers

Phase Transitions in Condensed Monolayers of Normal Chain Carboxylic Acids

Synthesis of (--)-Methyl 2D,4D,6D-Trimethylnonacosanoate and Identification of C32-Mycocerosic Acid as a 2,4,6,8-Tetramethyloctacosanoic Acid.

Some recent studies on the structural arrangements of lipids in surface layers and interphases.

The Qualitative Separation of Purines, Pyrimidines, and Nucleosides by Paper Chromatography.

Very Long Hydrocarbon Chains. I. The Synthesis of n-Dooctacontane and n-Hectane.