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ABSTRACT Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted [.sup.1]H solution NMR and UV-visible spectral [...]

Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted solution NMR and UV-visible spectral analysis to characterize the structural feature of a water-soluble, synthetic porphyrin i.e. tetrakis (p-sulfonatophenyl) porphyrin, TPPS4, and its interaction with different metal ions in aqueous solutions. The results indicate that tetrapyrrole and tetraphenyl rings in TPPS4 molecule form a co-planar electron conjugation system; transition-metal ions show stronger binding capacity than alkali and alkali-earth metal ions; the relative stabilities of TPPS4-metal ion complexes can be well assessed by NMR and UV-visible spectral data. [ABSTRACT FROM AUTHOR]

In the title compound, 3-[(4-amino-2-methyl-5-pyrimidin-1-io)methyl]-5-(2-hydroxy­ethyl)-4-methyl­thia­zolium(2+) bis(tetra­fluoro­borate), C12H18N4OS2+·2BF4−, the divalent thia­mine cation (in the F conformation) is associated with BF4− anions via two characteristic bridging interactions between the thia­zolium and pyrimidinium rings, i.e. C-H⃛BF4−⃛pyrimidinium and N-H⃛BF4−⃛thia­zolium interactions. Thi­amine mol­ecules are linked by N-H⃛O hydrogen bonds to form a helical chain structure. [ABSTRACT FROM AUTHOR]

An investigation into the interactions between thiamine monophosphate (TMP) and anions has resulted in the preparation and X-ray characterization of the compounds (TMP)(Hg2Br5)·0.5H2O (1) and (TMP)2(Hg3I8) (2). In each compound the TMP molecule exists as a monovalent cation in the usual F conformation. The halogenomercurate anions occur in two-dimensional (2-D) network in 1 or one-dimensional (1-D) chain in 2. In both 1 and 2, the structures consist of alternating cationic sheets of the hydrogen-bonded TMP molecules and anionic sheets of the polymeric halogenomercurate anions. The TMP molecule binds to the polymeric anions through the characteristic ‘anion bridge I’, C(2)&z.sbnd;H⋯X⋯pyrimidinium (X=Br in 1 and I in 2), and electrostatic interactions between electropositive S(1) and halogen atoms. The ‘anion bridge II’ of the type N(4′1)&z.sbnd;H⋯X⋯thiazolium (X=phosphate group) plays a role in stabilizing the molecular conformation. The biological implication of the host–guest-like complexation between TMP and polymeric anions is discussed. [Copyright &y& Elsevier]

Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted 1 H solution NMR and UV-visible spectral analysis to characterize the structural feature of a water-soluble, synthetic porphyrin i.e. tetrakis (p-sulfonatophenyl) porphyrin, TPPS 4 , and its interaction with different metal ions in aqueous solutions. The results indicate that tetrapyrrole and tetraphenyl rings in TPPS 4 molecule form a co-planar electron conjugation system; transition-metal ions show stronger binding capacity than alkali and alkali-earth metal ions; the relative stabilities of TPPS 4 -metal ion complexes can be well assessed by NMR and UV-visible spectral data.