Chemistry and Instrumental Chemistry

The research activities of the Chemistry group are mainly focused on the basic research in the field of the Inorganic chemistry and in the field of the Organic chemistry. Inorganic chemistry

• The research has largely developed in the chemistry of platinum and palladium and the results can be summarized as follows:

1. a) Synthesis, structural characterization and reactivity of organometallic complexes of Pt (II) and Pd (II) to trigonalbipyramidal geometry (TBP) of the type [PTX (R) (NN) (unsaturated)]. Stability of the five-coordinated species with respect to the dissociation of the olefinic unsaturated bond. Were also investigated the factors that determine the stability of the complexes with alkynes and CO five-coordinated. b) Synthesis of complex three coordinated complexes of Pt (0) and Pd (0) of the type [M (NN) (olefin)] and reactivity in oxidative eaddition reactions of various substrates. The method very versatile, allowed the preparation of: i) five-coordinated complex with hydrocarbylgroups functionalized which can not be added to the platinum with the methods based on lithium-organic precursors or Grignard reagents; ii) bimetallic complex with Pt-metal bond; iii) five-coordinated hydride complexes with a Pt-H bond. c) Synthesis and characterization of cationic hydrocarbylplatinum (II) and palladium (II) complexes with trigonalbipyramidal geometry of the type [MRL(N-N ') (unsaturated)] BF4 and study of their reactivity. These species give an insertion process (alkene, alkyne) in the MC(aryl) bond. The research has been further developed as part of interdisciplinary themes with the research group of Groundwater Research Center, focused on hydrochemical investigations of related aspects to hydrogeological, geochemical and microbiological characteristics of the aquifers.

In recent years the research has been mainly addressed to the following environmental issues: a)Heavy metals bioremediation of soils. Heavy metals have been excessively released into the environment due to rapid industrialization and have created great global concern. Thus remediation of heavy metal pollution deserves due attention. Different physical and chemical methods used for this purpose suffer from serious limitations like high cost, intensive labor, alteration of soil properties and disturbance of soil native microflora. In contrast, phytoremediation is a better solution to the problem. Phytoremediation is the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments.Heavy metals are not biodegradable; they accumulate in living tissues through the food web, causing global environmental problems and major threats to humans after chronic exposure. In some cases, plants have evolved strategies allowing them to grow in metal-contaminated soils, where they extract high concentrations of metals and store them in various tissues without signs of toxicity.

1. b) Wastewater treatment. Microalgae have a great potential in a wide variety of applications,concerning environmental ones, microalgae can play an important role in bioremediation of waste water and carbon dioxide sequestration. Microalgae are an important source of oils and other biomolecules that can be used in the production of biofuels and high-valued products. However, the use of microalgae in these green processes is still not economically viable. One of the main costs associated to microalgal production is related to the harvesting process, as it usually accounts for about 20–30% of total cost. The algae utilize the nitrogen and phosphorus in waste-water and, with sufficient light conditions, convert the CO₂ into biomass through photosynthesis. This makes microalgae very well suited to carbon mitigation, as their high growth rates can keep up with the continuous flow of CO₂ from thepowerplant. The aim is to analyze the biological fixation of carbon dioxide (CO₂) performed by a wastewater native microalgae culture in a pilot scale raceway pond (RP) using urban wastewater as liquid culture and a 20% CO₂ gas supplied to the pond during the daylight.

Inorganic chemistry

• Metabolic studies have been used in animal, plant and microbial systems to describe and understand a variety of biological effects, including response to environmental factor, diet, disease states, toxins or pharmaceutical agents, enhanced understanding of the results of increased or decreased gene expression, and taxonomic studies. Although the approach has been used for the past 15 years, the advent of more powerful chemical analytical equipment and techniques and enhanced chemometric methods have led to much more widespread use in recent years. Changes in the metabolite profile detected in biofluids or at a tissue level (animal or vegetal), are the result of very complex regulatory mechanism including changes in gene and protein expression levels, as well as physiological changes in response to external stimuli, disease, ageing, nutritional and other environmental changes. By profiling changes in metabolite composition it is possible to generate information about the overall systems response to such changes.

Nuclear magnetic resonance (NMR) spectroscopy provides a large amount of information regarding molecular structure, and novel software innovations have facilitated the unequivocal identification and absolute quantification of compounds within composite samples. Due to the size and complexity of metabolomics datasets, numerous chemometric methods are used to extract and display systematic variation. Coupled with pattern recognition techniques and plant-specific metabolite database, broad-scope metabolite analyses have emerged as functional genomics tools for novel gene discovery and functional characterization. Structure-activity relationship of biological compounds (SAR) allows to obtain information on conformational preferences and on the behavior of natural and synthetic biomolecules to determine the factors that govern or regulate the molecular recognition of such substances between them, or their interaction, in certain cases, with metal ions. Indeed, the specificity of molecular mechanisms recognition is the basis for the biological activity of many systems, such as for example enzyme-substrate complex, or the interaction between a receptor and a substrate. The reason for this specificity is related to the conformation assumed by one or both of the systems involved in the interaction and, therefore, one of the main objectives in the field of the study of such systems is represented by the identification of the responsible conformation of the function performed.These studies, along with those of predicting the behavior of biological systems of increasing complexity, allow to guide the researcher in "rational" design of new systems with specific properties and higher biological activity than the natural compounds.Such studies are often assisted by the use of solvent systems that simulate the receptor environment or promote, where intrinsically possible, their tendency to structure themselves. This research relies on the use of spectroscopic techniques (NMR) and energy minimization calculations. The research activity in the field of Organic chemistry (CHIM/06) is carried out in the field of natural compounds from marine origin and from plant origin and is focused to the extraction, isolation and chemical characterization of natural organic compounds possessing biological activities. In recent years much attention has been devoted to natural compounds from the edible plants (vegetable foods, spices or officinal plants), as potential "new" drugs to be used in human disease. Secondary metabolites are indeed responsible for the interesting biological activities and a number of phytochemicals were screened fortheir pharmacological properties as antitumor, antiviral, antibacterial, anti-inflammatory and antioxidant activity.Oxidative processes are considered the cause of many chronic diseases especially those involving excess of free radicals and reactive oxygen species (ROS).Thephytochemical analysis involves several steps with fractionation and purification of active extracts by consecutive chromatographic separations: direct chromatography (Silica gel) and reversed phase chromatography (RP18), Medium pressure chromatography (MPLC), Droplet counter-current chromatography (DCCC). The last step is the HPLC in direct phase and in reversed phase where pure compounds will be obtained.As far as the chemical characterization, the pure compound will be subjected to a series of spectroscopic experiments: UV, IR, CD. Mainly Nuclear Magnetic Resonance (NMR) with 1D and 2D experiments and Mass spectrometry will be used. Recently a Metabolomic analysis was applied to the study of some complex biological systems as the plants. The development of analytical instrumentations data processing and chemometrics tools simplifies the study of complex biological system on large-scale. During the metabolomic analysis, both primary and secondary metabolites are detected after a snapshot of all metabolome and a relative or absolute quantification can be done.

GENERAL AND INORGANIC CHEMISTRY (S.S.D. CHIM/03)

• Synthesis, structural characterization and reactivity of organometallic complexes of Pt (II) and Pd (II)
• Synthesis of complex three coordinated complexes of Pt (0) and Pd (0) of the type [M (NN) (olefin)] and reactivity in oxidative addition reactions
• Synthesis, characterization and reactivityof cationic hydrocarbyl platinum (II) and palladium (II) complexes with trigonal bipyramidal geometry.
• Hydrochemical investigations of related aspects to hydrogeological, geochemical and microbiological characteristics of the aquifers
• Heavy metalsbioremediation of soils
• Microalgal wastewater treatment and carbon dioxide sequestration.

BIOSTRUCTURAL CHEMISTRY (S.S.D. CHIM/03) The research can be described as follow:

• Structural characterization and SAR of neuromodulators and neurotransmitters.
• Structural characterization and SAR of cytoprotective peptides.
• Peptides with anti-tumor activity.
• Structural characterization and SAR of sweet proteins.
• Structural characterization and SAR of fragments of proteins that exert biological activity.
• Multivariate analysis of matrices from natural origin, through PCA (Principal component analysis) and PLS-DA (Partial least squares discriminant analysis) using the data of 1H Nuclear Magnetic Resonance (NMR).

ORGANIC CHEMISTRY (S.S.D. CHIM/06)

• Chemistry of bioactive natural compounds from plant sources (vegetable foods, spices, officinal plants : Isolation and structural characterization;
• Chemistry, analysis and biological activity of natural oligosaccharides (saponins, oligoglycosides, glycosilated flavonoids etc);
• Analysis of volatile organic components (VOC) in the essential oils from aromatic plants;
• Determination of the absolute configuration of stereocenters in natural compounds using simple chemical derivatization with chiral auxiliaries or through an appropriate synthetic pathway to obtain model compounds.
• Synthesis of chiral reagents in the sugar analysis.
• Multivariate analysis of matrices from natural origin, through PCA (Principal component analysis) and PLS-DA (Partial least squares discriminant analysis) using the data of 1H Nuclear Magnetic Resonance (NMR).

V. DE FELICE - Department of Chemistry, and Department of Civil, Building and Enviromental Engineering, University of Napoli "Federico II"
M. IORIZZI - Interdepartmental Service Centre for Instrumental Analysis (CSIAS), and Department of Pharmacy, University of Napoli "Federico II"
G. SAVIANO - Department of Chemistry and Department of Biological Sciences, University of Napoli "Federico II"; Institute of Biomolecular Chemistry of CNR, Pozzuoli (Na).