Rietveld analysis with the Monte Carlo method was used to estimate the crystal structure parameters of one of the polymorphs of titanylphthalocyanine (TiOPc). This polymorph is called TiOPc type C (C-TiOPc), and it is a low-photosensitive pigment used in electrophotograpy. In order to determine the relationship between crystal structure and photosensitivity, the crystal structure of C-TiOPc was estimated. The most probable crystal structure is a monoclinic unit cell, space group Cc: a=2.519 nm, b=0.385 nm, c=2.546 nm, β=90.3°, Z=4, d
calc.=1.54 g/cm3.
A nonapeptide with an Ala–(HO)Gly–Ala sequence has been synthesized via condensation of appropriately protected tripeptide units. 1H NMR and CD spectral data indicate that the nonapeptide has a disordered structure in DMSO and water. The peptide forms a 1 : 3 complex of iron(III) with hydroxamate groups at neutral pH when mixed with an aqueous iron(III) solution. The complex shows λmax at 410 nm with an ε of 2160 at pH 7. Alanine residues influence the hydroxamate groups to produce a chiral complex, the CD spectrum of which reveals bands at 355 nm (Δε+0.8) and 435 nm (Δε−1.8), showing a preference for the Δ-configuration around the iron.
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