The development of the Brazilian chemistry sector, during the last 30 years, is nowadays being attributed to PADCT (Science and Technology Development Program). Since the seventies, the Government took notice of the importance of research in chemistry for the Brazilian economy, therefore creating PADCT to support chemistry and chemical engineering among other areas of science and technology. Planning and implementation of the second phase of this program represented a real joint strategic planning. Since then, academic research and human resources education have experienced significant improvements. However, in the chemical trade, the deficit continues to grow, in spite of an almost constant ratio between importation costs and export revenues. Continued investments for research in the area remain necessary.

The data analyzed in this work were generated following the methodology developed by Molina et al.(J. Electroanal. Chem., 1979) for the calibration of a potentiometric system of measurement of hydrogen-ion concentrations resulting from neutralizations, at 25 ºC, of acidic or alkaline solutions at constant ionic strength (0.1 mol.l-1) held with NaClO4. The observed data present a serious deviation in relation to the mathematical model derived from the Nernst equation, for pH values ranging from 3 to 11, where pH=-log[H+]. We show that the minimization of the sum of the absolute values of the residuals gives estimates that are not influenced by outlying values.

Neste trabalho relatamos a preparação, por métodos mais eficientes e práticos, de derivados da 2,2’-bipiridina, que são importantes precursores para outros, tais como: 4,4’-dicarbóxi-2,2’-bipiridina (I), 6,6’-dicarbóxi-2,2’-bipiridina (II), 6,6’-dicarbotiamida - 2,2’-bipiridina (III), 4,4’-dinitro-N,N’-dióxido-2,2’-bipiridina (IV) e mono-N-óxido-2,2’-bipiridina (VII). A síntese dos ligantes inéditos 4,4’-diácido hidroxâmico-2,2’-bipiridina (V) e 6,6’-diácido hidroxâmico-2,2’-bipiridina (VI) é também relatada.

The preparation of key precursors for many 2,2’-bipyridine derivatives such as 4,4’-dicarboxy- 2,2’-bipyridine (I), 6,6’-dicarboxy-2,2’-bipyridine- acid (II), 4,4’-dinitro-2,2’-bipyridine-N,N-dioxide (III), 6,6’-dicarbothioamide-2,2’-bipyridine (IV) and mono-N-oxide-2,2’-bipyridine (VII) through more efficient methods is described. The syntheses of the novel ligands 4,4’-dihydroxamic-2,2’-bipyridine (V) and 6,6’-dihydroxamic-2,2’-bipyridine (VI) are also reported.

An appraisal has been conducted of the impact PADCT (Support Program for Scientific and Technological Development) has caused on brazilian Chemistry and Chemical Engineering over a ten years period (1985-1995). During this time PADCT invested US$ 87.5 million dollars to support both scientific and technolgical development of chemistry. The main results, from an academic point of view, has been the strengthening of support services for academic research, including libraries and analytical facilities, and a consequent increase of the number and quality of human resources trained at the graduate level as well as a significant increase in the number of scientific publications.

Um estudo potenciométrico e espectrofotométrico de complexos mistos de CuII, fisiologicamente interessantes, foi realizado envolvendo ácidos hidroxâmicos como ligantes primários (A) e ligantes secundários (B) representados por histamina ou pelos aminoácidos glicina e histidina. Todos são potencialmente capazes de formar quelatos com anéis de cinco ou seis membros. A constante de formação e o espectro de absorção no visível são calculados para cada uma das espécies identificadas, tanto binárias quanto ternárias. As estruturas mais prováveis das espécies mistas são propostas com base nas constantes de formação calculadas, na estabilização em relação às duas espécies binárias correspondentes, bem como nos espectros de absorção no visível. Ficou comprovado que os complexos de Cu-hidroxamato não favorecem significativamente a formação de complexos ternários com aminoácidos que possuem apenas os grupos amino e carboxilato; contudo, a formação de complexos ternários com a histidina é fortemente favorecida, devido à presença do grupo imidazol.

A potentiometric and spectrophotometric study of physiologically interesting CuII mixed ligand complexes has been performed involving hydroxamic acids as primary ligands (A) and secondary ligands (B) represented either by histamine or the aminoacids glycine and histidine. All are potentially able to form chelate complexes with either five or six membered rings. The formation constant and the visible absorption spectrum were calculated for each one of the identified species, both binary and mixed ones. The most probable structures of the mixed species are discussed based upon their formation constants, their stabilization with regard to the two binary species as well as their visible absorption. It was evidenced that Cu-hydroxamate complexes do not favour significantly mixed ligand complex formation with aminoacids having only the carboxylate and amino groups; however, these complexes are strongly formed with histidine, due to the presence of the imidazol group.