Volume 77, Issue 10

The 4th International Conference of the Chemical Societies of the South-Eastern European Countries (ICOSECS-4) was held in Belgrade, Serbia and Montenegro, from 18-21 July 2004, at the Faculty of Technology and Metallurgy, University of Belgrade. These conferences have become a biennial event: the first two were held in Halkidiki, Greece (1998 and 2000), and the third in Bucharest, Romania (2002). ICOSECS-4 was organized by the Serbian Chemical Society on behalf of the Society of Albanian Chemists, Union of Chemists of Bulgaria, Pancyprian Union of Chemists, Association of Greek Chemists, Society of Chemists and Technologists of Macedonia, Chemical Society of Montenegro, and Romanian Chemical Society. The title of the conference was Chemical Sciences in Changing Times: Visions, Challenges and Solutions . Within this broad title, there were contributions from all areas of chemistry. However, the main focus of the conference was reflected in three symposia: - Advanced materials: From fundamentals to application - The greening of chemistry: Pursuit of a healthy environment and safe food - Teaching and understanding chemistry: New concepts and strategies for changing times (dedicated to 150 years of teaching chemistry in Serbia) The meeting was organized under the auspices of the International Union of Pure and Applied Chemistry (IUPAC), the Federation of European Chemical Societies (FECS), the Ministry of Science and Environmental Protection of Serbia, and the Organization for the Prohibition of Chemical Weapons (OPCW). The president of IUPAC, Leiv Sydnes, and the president of FECS, Gabor Naray-Szabo, attended the conference and addressed the participants. Some 600 researchers from 26 countries took part in the conference. One of the reasons for this large attendance lies in the fact that the organizers of these conferences (the chemical societies of South-East Europe) have declared a commitment to keep the registration fee as low as possible. In comparison with prevailing fees at similar meetings, the ICOSECS-4 registration fee of 80 euros can be considered really modest; it included the book of abstracts, the welcome reception, a city sightseeing tour, and the conference dinner! The scientific program featured five plenary lectures: - John Fenn, Virginia Commonwealth University, Richmond, USA, the 2002 Nobel Laureate: "Electrospray wings for molecular elephants" - Peter Atkins, Oxford University, Oxford, UK: "Modern trends in chemical education" - C. N. R. Rao, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India: "New directions in the chemical design of materials" - Egon Matijevic, Clarkson University, Potsdam, USA: "Mechanisms of formation of uniform fine particles and their applications" - Ivano Bertini, University of Florence, Florence, Italy: "From genomes to cellular mechanisms and drug design" In addition to the plenary lectures, the program included 38 invited lectures and 25 oral and 437 poster presentations. Brief summaries of all contributions were published in a two-volume book of abstracts. As already mentioned, the organizers put together a rich social program, which included a welcome reception in the historic City Hall (featuring a recital of the Simonuti Trio), a boat sightseeing tour of Belgrade, and a conference dinner with live music and dancing. The next conference, ICOSECS-5, will be organized by the Society of Chemists and Technologists of Macedonia in 2006. Teodor Ast Conference Editor and Chairman of the International Scientific Committee

Inorganic open-framework materials are discussed as a case study in the chemical design of materials. Investigations of open-framework zinc phosphates have demonstrated that the formation of the complex 3D architectures may involve a process wherein 1D ladders or chains, and possibly 0D monomers comprising four-membered rings, transform to the higher-dimensional structures. The 1D ladder and the four-membered rings appear to be important building units of these structures. At one stage of the building-up process, spontaneous self-assembly of a low-dimensional structure such as the ladder could occur, followed by the crystallization of a 3D structure. Accordingly, many of the higher-dimensional structures retain structural features of the 0D or 1D structure. It is significant that a four-membered ring zinc phosphate spontaneously yields a linear chain phosphate at room temperature, on addition of piperazine, the chain transforming to a sodalite-type 3D structure under mild conditions. The occurrence of a hierarchy of structures from 0-3 dimensions is found in open-framework metal oxalates as well. Interestingly, the 3D sodalite structure is generated readily by the assembly of metal squarates, possessing the four-membered ring motif. It is noteworthy that open-framework structures are also formed by oxyanions such as sulfate, selenite, and selenate. Transformations of molecules to complex architectures are a worthy area of study, defining a new direction in the chemistry of materials.

Self-assembly in morphological organization of various fullerene derivatives affords different supramolecular architectures. Nanospheres, tubules, and bundles of nanorods are formed depending on the nature of the organic group in the fullerene unit. The current work highlights an efficient method to fabricate almost perfect and uniformly shaped nanocrystals in a novel connection between spherical fullerene-based materials and fibrous nanotubes. In a parallel research line, carbon nanotubes (CNTs) have been functionalized using 1,3-dipolar cycloaddition of azomethine ylides. The organically functionalized CNTs, having improved solubility and potential for applications, are characterized by standard analytical methods as well as microscopy techniques.

Oligonuclear complexes as well as coordination polymers with various network topologies can be obtained by using homo- or heterobinuclear complexes as starting materials. These building blocks are stable complexes, where the metal ions are held together by compartmental ligands, or alkoxo-bridged Cu(II) species. The binuclear nodes can be connected through appropriate exo -dentate ligands, or through metal-containing anions (e.g., [M(CN) 6 ] 3- , M = Cr III , Fe III , Co III ). A rich variety of 3d-3d and 3d-4f heterometallic complexes, with interesting architectures and topologies of the spin carriers, has been obtained. A particular case is the one concerning the 3d-4f binuclear nodes. Following this strategy, we were able to obtain coordination polymers containing three different spin carriers (2p-3d-4f; 3d-3d'-4f).

A new 2D zinc phosphate [H 3 NCH(CH 3 )CH 2 NH 3 ] 2+ 0.75 [COOH(CH 2 )COOH] 0.25 (Zn 3 P 3 O 11 OH) 2- * 0.5NH 4 + consists of zinc phosphate layers, which are intercalated by diprotonated 1,2-diaminopropane, malonic acid, and NH 4 + ions. The inorganic layers are composed of alternating ZnO 4 and PO 4 (PO 3 OH) tetrahedra that form 8-membered ring apertures. The intercalated species strongly interact with the zinc phosphate layers through hydrogen bonds, which is a key factor in stabilizing the structure. Crystal data: monoclinic, P 2 1 /a, a = 8.3457(1) Å, b = 16.8953(3) Å, c = 10.1817(2) Å, β = 95.3121(8)°, Z = 4, R = 0.0423.

The mechanism of the reaction between amines with dimethyl carbonate (DMC) has been investigated. Whereas in the absence of bases, they give methylation and carboxymethylation reactions without selectivity (B Al 2 and B Ac 2 mechanisms, respectively), in the presence of bases, the B Ac 2 mechanism prevails. The carbamate already formed reacts further with DMC via the B Al 2 mechanism to give the corresponding N -methyl derivative. Such pronounced double selectivity has been explained in terms of Pearson's Hard-Soft Acid-Base (HSAB) theory. Accordingly, N -methylcarbamates have been prepared from primary aliphatic and aromatic amines, either at reflux temperature of DMC (90 °C) or at 230 °C in autoclave. The reaction can be carried out in one step or through the isolation of the carbamate and the subsequent methylation reaction with DMC. This method is the direct synthesis, in high yield and selectivity, of secondary N -methylamines from the corresponding primary amines.

Photodegradation of coumaphos and azinphos-methyl in the air, in oxygen, and in nitrogen atmosphere (quartz reactor equipped with six 18-W lamps with the maximum emission intensity at 310 nm) was studied. The fastest reaction occurred with coumaphos in nitrogen atmosphere (complete decomposition in 10 min), where the formation of a new compound was also detected by high-performance liquid chromatography (HPLC). In the case of azinphos-methyl, no additional signals in HPLC chromatogram were observed. The rearrangement mechanism, involving a triplet-state activation complex and the formation of an acetylcholinesterase (AChE)-inhibiting oxo analog of coumaphos was verified and confirmed by laser flash photolysis. The suitability of bioanalytical flow-injection analysis (FIA) systems, based on AChE inhibition and spectrophotometric or thermal lens spectrometric detection for rapid and sensitive screening in food quality control was demonstrated. Owing to the high sensitivity of thermal lens spectrometry (TLS), several steps in sample preparation can be avoided (preconcentration, purification, isolation) and incubation times reduced. High sample throughputs (10 h -1 ) are, however, also achievable for medium toxic oxo organophosphorus (OP) pesticides using spectrophotometric detection providing limits of detection (LODs) at the level of 10 ppb malaoxon equivalents, which is still about 50 times below maximal residue levels. Testing of the method for practical application on a set of 60 samples gave no false negative results and a level of 1.7 % false positives.

The present study focuses on the use of phosphate-containing compounds, such as apatites, as stabilization additives for solid industrial wastes. The examined highly toxic waste contained mainly lead, iron, and bromides. Phosphates (synthetic or natural), when used as additives, were found to diminish the release of lead from the stabilized waste below the respective legislative concentration limits, following the application of DIN 38414 standard leaching method and within the range of pH values 7.5-10.5. The respective synthetic compounds of lead, PbO and Pb(OH)Br, existing also in the solid waste, were additionally studied during simulation experiments, in order to examine the possible mechanisms of waste stabilization, by using the same additives (phosphates). The obtained results showed the possibility of another parallel mechanism, different from that proposed in the literature, which is the sorption of aqueous lead ions onto the apatite surface. It was suggested that lead can be also transformed into the less soluble solid phases through the interaction (surface crystallization) of exposed lead surface with the aqueous environment. The formation of new crystals onto the surface of lead phase was sufficiently fast, especially in the case of natural phosphate mineral additive, most probably due to the presence of calcite, which supplies part of its carbonate content for the formation of respective lead carbonate solid phases.

In this report, the status quo and recent progress in electrokinetics are reviewed. Practical rules are recommended for performing electrokinetic measurements and interpreting their results in terms of well-defined quantities, the most familiar being the z-potential or electrokinetic potential. This potential is a property of charged interfaces, and it should be independent of the technique used for its determination. However, often the z-potential is not the only property electrokinetically characterizing the electrical state of the interfacial region; the excess conductivity of the stagnant layer is an additional parameter. The requirement to obtain the z-potential is that electrokinetic theories be correctly used and applied within their range of validity. Basic theories and their application ranges are discussed. A thorough description of the main electrokinetic methods is given; special attention is paid to their ranges of applicability as well as to the validity of the underlying theoretical models. Electrokinetic consistency tests are proposed in order to assess the validity of the z-potentials obtained. The recommendations given in the report apply mainly to smooth and homogeneous solid particles and plugs in aqueous systems; some attention is paid to nonaqueous media and less ideal surfaces.