Cytidine 5 - , 8.5 hydrate, crystal

If the crystal structures and hydrogen-bonding patterns of uridine and thymidine and their simpler derivatives are compared with those of cytidine, it becomes obvious that the -NH2 functional group has a characteristic influence. The nucleosides without the -NH2 groups have less than average hydrated crystals, although the one nucleotide represented, uridine-3 -monophosphate, crystallizes as a monohydrate. 

Selected crystal structures of cytidlne and its derivatives. The cytidine-related nucleoside and nucleotide crystal structures for which reliable hydrogen-bond patterns can be reported include five nucleotides. Amongst the nucleotides there is more variety than with the uridine compounds. There are three hydrates, four hydrochlorides, and a nitrate. The conjugated NH2 group is always involved as a donor, but never as an acceptor. Several different configurations are observed ... 

X-ray crystal results on cjiiosine itself ° (anhydrous and mono-hydrate), its complexes with different partners,cytidine, and cytidine 2, 3 -cyclic phosphateall indicate its existence in the lactam-amine form (2). In a number of crystals the cytosine ring is protonated, invariably at In cytosine 5-acetic acid half of the molecules... 

A study of the relaxational transitions and related heat capacity anomalies for galactose and fructose has been described which employs calorimetric methods. The kinetics of solution oxidation of L-ascorbic acid have been studied using an isothermal microcalorimeter. Differential scanning calorimetry (DSC) has been used to measure solid state co-crystallization of sugar alcohols (xylitol, o-sorbitol and D-mannitol), and the thermal behaviour of anticoagulant heparins. Thermal measurements indicate a role for the structural transition from hydrated P-CD to dehydrated P-CD. Calorimetry was used to establish thermodynamic parameters for (1 1) complexation equilibrium of citric acid and P-CD in water. Several thermal techniques were used to study the decomposition of p-CD inclusion complexes of ferrocene and derivatives. DSC and derivative thermogravimetric measurements have been reported for crystalline cytidine and deoxycytidine. Heats of formation have been determined for a-D-glucose esters and compared with semiempirical quantum mechanical calculations. ... 

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