Structure of molecular adducts of inorganic salts. VIII. Thiourea complexes of cadmium nitrate

In the system Cd(NO3)2-tu-H2O, tu = thiourea, the structures of three Cd(NO3)2 · ntu (n=2, 4) addition compounds were carried out. Monoclinic Cd(NO3)·2tu, space group P21/n, a = 4.267(1)Å, b = 11.956(1) Å, c = 11.330(1) Å, β = 100.22(6)°. The crystal structure is built up of neutral [Mtu2 ·(NO3)2] centrosymmetric complexes. The two polymorphic modifications when n = 4 coexist under ambient conditions. They are both monoclinic, space group P21/c, with cell parameters are a=21.380(3)Åβ =5.975(1) Å, c = 17.531(4) Å, β = 122.56(2)° for (I) and a = 12.811(3) Å, b= 9.157(1)Å, c = 15.770(2)Å, β = 91.20(1)° for (II). Their structures consist of complex [Mtu4] 2 + cations and NO3 - anions, linked through extensive networks of weak hydrogen bonds which hold the structural units together.

Crystal structures of Cd(ReO4)2 · 4Urea, Cd(ReO4)2 · 6Urea and Ca(ReO4)2 · 5Urea. Synthesis and characterization of urea adducts from the systems M(ReO4)2-Urea-H2O, M = Ca, Sr, Ba, Pb and Cd

The crystal structutes of Cd(ReO4)2 · 4Urea, Cd(ReO4)2 · 6Urea and Ca(ReO4)2 · 5Urea were solved. Cd(ReO4)2 · 4Urea consists of discrete neutral [Cd(ReO4)2L4] (L = Urea) clusters. Ca(ReO4)2 · 5Urea and Cd(ReO4)2 · 6Urea are built up of cationic [Ca(ReO4)L5]+ and [CdL6]2+ clusters, respectively, and ReO4- anions, interlinked by an extensive network of H-bonds. The octahedral coordination of M atoms is most regular in Cd(ReO4)2 · 6Urea and most distorted in Ca(ReO4)2 · 5Urea.

With the synthesis and X-ray analysis of these new urea adducts the investigation of the systems M(ReO4)2-Urea-H2O, M = Ca, Sr, Ba, Pb and Cd, was accomplished. This paper represents and a review of the synthesis, X-ray study and IR characterisation of the stable phases from the mentioned systems.

A possible correlation of electro-optic changes with the deformability of erythrocytes

A novel electro-optical technique for deformability measurement is described. This method is faster and more convenient than "standard" procedures. Erythrocytes (RBC, 10(6) cells/mL suspended in isotonic sucrose 10%, ionic strength 10(-4) M/L, pH 6.5) are ordered in an electric field (E = 10(4) Vp-p/m, v = 10(3) Hz) following the field direction, as a result of an induced electric dipole moment. After the switching off of the electric field, a certain time is required for the electro-optic effect to subside. Under the action of thermal motion, the suspended erythrocytes virtually return to their initial unordered state. The decay time (return time) is the investigated parameter. Results show that if erythrocyte deformability is reduced, the return time is longer than in control RBC. Suspensions of erythrocytes with reduced deformability, achieved by treatment with glutaraldehyde at concentrations ranging from 10(-8) to 10(-1) M/L, are measured. The suggested electro-optic method has good precision and requires a very small quantity of blood (about 0.1 mL), which makes it potentially useful in clinical practice.