Piero Macchi

Bio: Piero Macchi is an academic researcher from Polytechnic University of Milan. The author has contributed to research in topics: Electron density & Atoms in molecules. The author has an hindex of 35, co-authored 175 publications receiving 4963 citations. Previous affiliations of Piero Macchi include Istituto Italiano di Tecnologia & University of Milan.

Experimental Electron Density in a Transition Metal Dimer: Metal−Metal and Metal−Ligand Bonds

Abstract: The accurate experimental electron density distribution of Co2(CO)6(AsPh3)2 has been determined through X-ray diffraction at T = 123 K. Metal−metal and metal−ligand bonds have been investigated by means of deformation densities and the quantum theory of atoms in molecules. The “expected” lack of charge accumulation in the deformation density map is “contradicted” by the presence of a bond critical point and a bond path line linking the two Cobalt atoms, in agreement with theoretical predictions on similar compounds. A careful analysis of the properties of ρ(r) at the bond critical points and of the Laplacian distribution along the bond paths has allowed the full characterization of all bonds in the title compound and, in particular, to discard the apparently straightforward classification of Co−Co as a closed-shell interaction. The radial shape of the atomic Laplacian makes (covalent or polar) shared interactions similar to donor−acceptor ones when at least one “heavy atom” is concerned. Thus, even if it ...

Modern Charge-Density Analysis

Abstract: A guided tour through modern charge density analysis.- Electron densities and related properties from the ab-initio simulation of crystalline solids.- Modeling and analysing thermal motion in experimental charge density studies.- Spin and the Complementary Worlds of Electron Position and Momentum Densities.- Past, present and future of charge density and density matrix refinements.- Using wavefunctions to get more information out of diffraction experiments.- Local Models for Joint Position and Momentum Density Studies.- Magnetization densities in material science.- Beyond Standard Charge Density Topological Analyses.- On the Interplay Between Real and Reciprocal Space Properties.- Intermolecular interaction energies from experimental charge density studies.- Chemical Information from Charge Density Studies.- Charge density in materials and energy science.- A generic force field based on Quantum Chemical Topology.- Frontier Applications of Experimental Charge Density and Electrostatics to Bio-Macromolecules.- Charge densities and crystal engineering.- Electron Density Topology of Crystalline Solids at High Pressure.- Bonding changes along solid-solid phase transitions using the Electron Localization Function approach.- Multi-temperature electron density studies.- Transient Charge Density Maps from Femtosecond X-Ray Diffraction.- Charge density and chemical reactions: a unified view from Conceptual DFT.

Complex Interwoven Polymeric Frames from the Self-Assembly of Silver(I) Cations and Sebaconitrile

Abstract: Interwoven networks have been isolated from the self-assembly of the flexible long-chain sebaconitrile (1,10-decanedinitrile) and different silver(I) salts. These networks include an eightfold interpenetrated diamondoid frame (I), a fourfold interwoven 3D four-connected frame topologically related to the prototypical SrAl2 (II), an infinitely catenated 2D multilayer (III), and a 3D entangled array (IV).

Reticular synthesis and the design of new materials

Abstract: The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.

The hydrogen bond in the solid state.

Abstract: The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles

Abstract: 5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3

C-H bond functionalization: emerging synthetic tools for natural products and pharmaceuticals

Abstract: The direct functionalization of C-H bonds in organic compounds has recently emerged as a powerful and ideal method for the formation of carbon-carbon and carbon-heteroatom bonds. This Review provides an overview of C-H bond functionalization strategies for the rapid synthesis of biologically active compounds such as natural products and pharmaceutical targets.