scholarly journals Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4331
Author(s):  
David B. Hobart ◽  
Michael A. G. Berg ◽  
Hannah M. Rogers ◽  
Joseph S. Merola

The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and 1H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. The molecular geometries of the products are discussed. Except for the alanine complex, all complexes incorporate water molecules into the extended lattice and exhibit N-H···O and/or O···(HOH)···O hydrogen bonding interactions. The non-covalent interactions are discussed in terms of the extended lattice structures exhibited by the structures.

Author(s):  
Asiloé J. Mora ◽  
Lusbely M. Belandria ◽  
Gerzon E. Delgado ◽  
Luis E. Seijas ◽  
Angel Lunar ◽  
...  

Single-crystal X-ray diffraction and quantum mechanical theories were used to examine in detail the subtle nature of non-covalent interactions in the [2:1:1] multicomponent crystal of 1,1-aminocyclopentanecarboxylic acid:oxalic acid:water. The crystal, which is a hydrate salt of the amino acid with the hydrogen-oxalate ion, also contains the zwitterion of the amino acid in equal proportions. It was found that a dimeric cation [Acc5(Z)...Acc5(C)]+bonded by an O—H...O hydrogen bond exists due to a charge transfer between acid and carboxylate groups. The three-dimensional crystal is built by blocks stacked along the [101] direction by dispersion interactions, with each block growing along two directions: a hydrogen oxalate HOX−...HOX−catameric supramolecular structure along the [010] direction; and double ...HOX−—W—[Acc5(Z)... Acc5(C)]+... chains related by inversion centers along the [1 0 {\bar 1}] direction. A PBE-DFT optimization, under periodic boundary conditions, was carried out. The fully optimized structure obtained was used to extract the coordinates to calculate the stabilization energy between the dimers under the crystal field, employing the M062X/aug-cc-pVTZ level of theory. The non-covalent index isosurfaces employed here allow the visualization of where the hydrogen bond and dispersion interactions contribute within the crystal. The crystal atomic arrangements are analyzed by employing the Atoms in Molecules and electron localization function theories. Within this context, the presence of density bond critical points is employed as a criterion for proving the existence of the hydrogen bond and it was found that these results agree with those rendered by the crystallographic geometrical analysis, with only three exceptions, for which bond critical points were not found.


Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1942
Author(s):  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen

Porphyrinic compounds are widespread in nature and play key roles in biological processes such as oxygen transport in blood, enzymatic redox reactions or photosynthesis. In addition, both naturally derived as well as synthetic porphyrinic compounds are extensively explored for biomedical and technical applications such as photodynamic therapy (PDT) or photovoltaic systems, respectively. Their unique electronic structures and photophysical properties make this class of compounds so interesting for the multiple functions encountered. It is therefore not surprising that optical methods are typically the prevalent analytical tool applied in characterization and processes involving porphyrinic compounds. However, a wealth of complementary information can be obtained from NMR spectroscopic techniques. Based on the advantage of providing structural and dynamic information with atomic resolution simultaneously, NMR spectroscopy is a powerful method for studying molecular interactions between porphyrinic compounds and macromolecules. Such interactions are of special interest in medical applications of porphyrinic photosensitizers that are mostly combined with macromolecular carrier systems. The macromolecular surrounding typically stabilizes the encapsulated drug and may also modify its physical properties. Moreover, the interaction with macromolecular physiological components needs to be explored to understand and control mechanisms of action and therapeutic efficacy. This review focuses on such non-covalent interactions of porphyrinic drugs with synthetic polymers as well as with biomolecules such as phospholipids or proteins. A brief introduction into various NMR spectroscopic techniques is given including chemical shift perturbation methods, NOE enhancement spectroscopy, relaxation time measurements and diffusion-ordered spectroscopy. How these NMR tools are used to address porphyrin–macromolecule interactions with respect to their function in biomedical applications is the central point of the current review.


2021 ◽  
Vol 25 ◽  
Author(s):  
Jun Zheng ◽  
Yan Mei Jin ◽  
Xi Nan Yang ◽  
Lin Zhang ◽  
Dao Fa Jiang ◽  
...  

: Single-crystal X-ray diffraction analysis, nuclear magnetic resonance (NMR), and other characterization methods are used to characterize the complexes formed by cyclopentano-cucurbit[6]uril (abbreviated as CyP6Q[6]) as a host interacting with p-aminobenzenesulfonamide (G1), 4,4'-diaminobiphenyl (G2), and (E)-4,4'-diamino-1,2-diphenylethene (G3) as guests, respectively. The experimental results show that these three aromatic amine molecules have the same interaction mode with CyP6Q[6], interacting with its negatively electric potential portals. The supramolecular interactions include non-covalent interactions of hydrogen bonding and ion-dipole between host and guest molecules. CdCl2 acts as a structureinducing agent to form self-assemblies of multi-dimensional and multi-level supramolecular frameworks that may have potential applications in various functional materials.


Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6731
Author(s):  
Haruki Inoue ◽  
Yuga Yamashita ◽  
Yoshiki Ozawa ◽  
Toshikazu Ono ◽  
Masaaki Abe

Two hexanuclear paddlewheel-like clusters appending six carboxylic-acid pendants have been isolated with the inclusion of polar solvent guests: [Cu6(Hmna)6]·7DMF (1·7DMF) and [Ag6(Hmna)6]·8DMSO (2·8DMSO), where H2mna = 2-mercaptonicotininc acid, DMF = N,N’-dimethylformamide, and DMSO = dimethyl sulfoxide. The solvated clusters, together with their fully desolvated forms 1 and 2, have been characterized by FTIR, UV–Vis diffuse reflectance spectroscopy, TG-DTA analysis, and DFT calculations. Crystal structures of two solvated clusters 1·7DMF and 2·8DMSO have been unambiguously determined by single-crystal X-ray diffraction analysis. Six carboxylic groups appended on the clusters trap solvent guests, DMF or DMSO, through H-bonds. As a result, alternately stacked lamellar architectures comprising of a paddlewheel cluster layer and H-bonded solvent layer are formed. Upon UV illumination (λex = 365 nm), the solvated hexasilver(I) cluster 2·8DMSO gives intense greenish-yellow photoluminescence in the solid state (λPL = 545 nm, ΦPL = 0.17 at 298 K), whereas the solvated hexacopper(I) cluster 1·7DMF displays PL in the near-IR region (λPL = 765 nm, ΦPL = 0.38 at 298 K). Upon complete desolvation, a substantial bleach in the PL intensity (ΦPL < 0.01) is observed. The desorption–sorption response was studied by the solid-state PL spectroscopy. Non-covalent interactions in the crystal including intermolecular H-bonds, CH···π interactions, and π···π stack were found to play decisive roles in the creation of the lamellar architectures, small-molecule trap-and-release behavior, and guest-induced luminescence enhancement.


Foods ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 360 ◽  
Author(s):  
Chun-Min Ma ◽  
Xin-Huai Zhao

The non-covalent interactions between a commercial whey protein isolate (WPI) and two bioactive polyphenols galangin and genistein were studied at pH 6.8 via the multi-spectroscopic assays and molecular docking. When forming these WPI-polyphenol complexes, whey proteins had changed secondary structures while hydrophobic interaction was the major driving force. Detergent sodium dodecyl sulfate destroyed the hydrophobic interaction and thus decreased apparent binding constants of the WPI-polyphenol interactions. Urea led to hydrogen-bonds breakage and protein unfolding, and therefore increased apparent binding constants. Based on the measured apparent thermodynamic parameters like ΔH, ΔS, ΔG, and donor-acceptor distance, galangin with more planar stereochemical structure and random B-ring rotation showed higher affinity for WPI than genistein with location isomerism and twisted stereochemical structure. The molecular docking results disclosed that β-lactoglobulin of higher average hydrophobicity had better affinity for the two polyphenols than α-lactalbumin of lower average hydrophobicity while β-lactoglobulin possessed very similar binding sites to the two polyphenols. It is concluded that polyphenols might have different non-covalent interactions with food proteins, depending on the crucial polyphenol structures and protein hydrophobicity.


Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 515 ◽  
Author(s):  
David B. Hobart ◽  
Joseph S. Merola ◽  
Hannah M. Rogers ◽  
Sonia Sahgal ◽  
James Mitchell ◽  
...  

Palladium(II) acetate reacts with proline and proline homologs in acetone/water to yield square planar bis-chelated palladium amino acid complexes. These compounds are all catalytically active with respect to oxidative coupling of olefins and phenylboronic acids. Some enantioselectivity is observed and formation of products not reported in other Pd(II) oxidative couplings is seen. The crystal structures of nine catalyst complexes were obtained. Extended lattice structures arise from N-H••O or O••(HOH)••O hydrogen bonding. NMR, HRMS, and single-crystal XRD data obtained on all are evaluated.


RSC Advances ◽  
2018 ◽  
Vol 8 (67) ◽  
pp. 38445-38454 ◽  
Author(s):  
Andrea Gionda ◽  
Giovanni Macetti ◽  
Laura Loconte ◽  
Silvia Rizzato ◽  
Ahmed M. Orlando ◽  
...  

A small conformational change in the asymmetric unit has a significant effect on how non-covalent interactions determine (i) the crystal packing and (ii) the effect of T on the relative balance of electrostatics and dispersion–repulsions.


2009 ◽  
Vol 1189 ◽  
Author(s):  
Mihail Barboiu ◽  
Adinela Cazacu ◽  
Simona Mihai ◽  
Yves-Marie Legrand ◽  
Arie van der Lee

AbstractDynamic constitutional hybrid materials in which the functional self-organized macrocycles are reversibly connected with the inorganic silica mesopores through hydrophobic non-covalent interactions. Supramolecular columnar self-organized architectures confined within scaffolding hydrophobic silica mesopores can be structurally determined by using X-ray diffraction techniques.


2015 ◽  
Vol 30 (4) ◽  
pp. 357-361 ◽  
Author(s):  
Bruno Z. Mascaliovas ◽  
Fernando R.G. Bergamini ◽  
Alexandre Cuin ◽  
Pedro P. Corbi

Synthesis and structural characterization of a novel palladium Pd(II) complex with the amino acid L-citrulline (Cit, C6H13N3O3) are presented in this paper. Elemental analysis indicates a 1:2 metal/ligand molar composition for the complex, with the molecular formula PdC12H24N6O6. The compound was also characterized by infrared (IR) spectroscopic measurements and the crystal structure has been solved by powder X-ray diffraction data with simulated annealing strategy in real space. The Pd(II) complex crystallizes in the triclinic system with space group P-1 and cell parameters a = 4.6493(4) Å, b = 5.222(4) Å, c = 18.040(2) Å, α = 77.41(6)°, β = 94.72(7),° and γ = 101.45(7)°. The crystal structure confirms the presence of Pd(II) ions in a nearly square planar environment and the molecular formula with deprotonated citrulline as proposed by analytical and spectroscopic data.


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