Molecular Dynamics Simulations of the Self-Assembly of Tetraphenylporphyrin-Based Monolayers and Bilayers at a Silver Interface

A theoretical study of the adsorption and dynamics of tetraphenylporphyrins on a Ag(111) substrate and the subsequent aggregation of the formed monolayers with fullerene molecules is reported. Classical molecular dynamics simulations were able to reveal the various phases of monolayer and bilayer formation and succeeded in identifying all the interactions responsible for self-assembling and surface binding. Possible supramolecular configurations extracted from the molecular dynamics trajectories were classified and characterized in detail and revealed to be in satisfactory agreement with experimental data

Density Functional Theory Study of the Binding Capability of Tris(pyrazol-1-yl)methane toward Cu(I) and Ag(I) Cations

Density functional theory (DFT) has been used to look into the electronic structure of [M(tpm)]+ molecular ion conformers (M = Cu, Ag; tpm = tris(pyrazol-1-yl)methane) and to study the energetics of their interconversion. Theoretical data pertaining to the free tpm state the intrinsic instability of its κ3-like conformation, thus indicating that, even though frequently observed, the κ3-tripodal coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the κ3-like tpm conformer. It is also found that the energy barrier for the κ2-[M(tpm)]+ → κ3-[M(tpm)]+ conversion is negligible. As far as the bonding scheme is concerned, the tpm → M(I) donation, both σ and π in character, is the main source of the M(I)−tpm bonding, whereas back-donation from completely occupied M(I) d orbitals into tpm-based π* levels plays a negligible role

Density Functional Theory Study of the Binding Capability of Tris(pyrazol-1-yl)methane toward Cu(I) and Ag(I) Cations

Density functional theory (DFT) has been used to look into the electronic structure of [M(tpm)]+ molecular ion conformers (M = Cu, Ag; tpm = tris(pyrazol-1-yl)methane) and to study the energetics of their interconversion. Theoretical data pertaining to the free tpm state the intrinsic instability of its κ3-like conformation, thus indicating that, even though frequently observed, the κ3-tripodal coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the κ3-like tpm conformer. It is also found that the energy barrier for the κ2-[M(tpm)]+ → κ3-[M(tpm)]+ conversion is negligible. As far as the bonding scheme is concerned, the tpm → M(I) donation, both σ and π in character, is the main source of the M(I)−tpm bonding, whereas back-donation from completely occupied M(I) d orbitals into tpm-based π* levels plays a negligible role

Molecular, Electronic, and Crystal Structures of Self-Assembled Hydrothermally Synthesized Zn(II)−Mercaptonicotinate: A Combined Spectroscopic and Theoretical Approach

A Zn(II) 2-mercaptonicotinate coordination polymer (Zn1), with Zn(II) ions chelated by both sulfur and oxygen in a distorted square pyramidal environment, and a molecular Zn(II) 2-hydroxynicotinate complex (Zn2) were synthesized by the reaction of zinc acetylacetonate with 2-mercaptonicotinic (Zn1) and 2-hydroxynicotinc (Zn2) acid, respectively, under hydrothermal conditions. The crystal structures of Zn1 and Zn2 were determined by single crystal X-ray diffraction measurements. Dispersion-corrected density functional theory (DFT) calculations reproduce very well the experimental structures and show that Zn1 is stable against hydration, whereas Zn2 is stable against dehydration over wide ranges of temperature and pressure, in agreement with thermogravimetric analysis results. The electronic structure of the two compounds is computed with the DFT+U method. The theoretical valence band agrees well with the X-ray photoelectron spectroscopy experiments. Furthermore, the band gap of Zn1 is found to be narrower than that of Zn1 and is characterized by the presence of sulfur lone pairs at the edge of the valence band

Molecular, Electronic, and Crystal Structures of Self-Assembled Hydrothermally Synthesized Zn(II)−Mercaptonicotinate: A Combined Spectroscopic and Theoretical Approach

A Zn(II) 2-mercaptonicotinate coordination polymer (Zn1), with Zn(II) ions chelated by both sulfur and oxygen in a distorted square pyramidal environment, and a molecular Zn(II) 2-hydroxynicotinate complex (Zn2) were synthesized by the reaction of zinc acetylacetonate with 2-mercaptonicotinic (Zn1) and 2-hydroxynicotinc (Zn2) acid, respectively, under hydrothermal conditions. The crystal structures of Zn1 and Zn2 were determined by single crystal X-ray diffraction measurements. Dispersion-corrected density functional theory (DFT) calculations reproduce very well the experimental structures and show that Zn1 is stable against hydration, whereas Zn2 is stable against dehydration over wide ranges of temperature and pressure, in agreement with thermogravimetric analysis results. The electronic structure of the two compounds is computed with the DFT+U method. The theoretical valence band agrees well with the X-ray photoelectron spectroscopy experiments. Furthermore, the band gap of Zn1 is found to be narrower than that of Zn1 and is characterized by the presence of sulfur lone pairs at the edge of the valence band

Water-Soluble [Tc(N)(PNP)] Moiety for Room-Temperature ^99mTc Labeling of Sensitive Target Vectors

The incorporation of bioactive molecules into a water-soluble [99mTc]­[Tc­(N)­(PNP)]-based mixed compound is described. The method, which exploits the chemical properties of the new [99mTc]­[Tc­(N)­(PNP3OH)]2+ synthon [PNP3OH = N,N-bis­(di-hydroxymethylenphosphinoethyl)­methoxyethylamine], was successfully applied to the labeling of small, medium (cysteine-functionalized biotin and c-RGDfK pentapeptide), and large molecules. Apomyoglobin was chosen as a model protein and derivatized via site-specific enzymatic reaction catalyzed by transglutaminase (TGase) with the H-Cys-Gly-Lys-Gly-OH tetrapeptide for the insertion in the protein sequence of a reactive N-terminal Cys for 99mTc chelation. Radiosyntheses were performed under physiological conditions at room temperature within 30 min. They were reproducible, highly specific, and quantitative. Heteroleptic complexes are hydrophilic and stable. Biodistributions of the selected compounds show favorable pharmacokinetics within 60 min post-injection and predominant elimination through the renal-urinary pathway. In a wider perspective, these data suggest a role of the [99mTc]­[Tc­(N)­(PNP)] technology in the labeling of temperature-sensitive biomolecules, especially targeting proteins for SPECT imaging