Waldemar Goldeman

Aminophosphinic acids in a pyridine series : Cleavage of pyridine-2- and pyridine-4-methyl(amino)phosphinic acids in acidic solutions

The synthesis of a series of new pyridine aminomethylphosphinic acids is described. These compounds were obtained in the reaction of the corresponding pyridine aldehydes with primary amines and with ethyl phenylphosphinate, or methylphosphinate, in the presence of bromotrimethylsilane. In aqueous, strong acid solutions, pyridine aminophosphinic acids were split, forming the phenyl-, or methylphosphonic, acid and the corresponding secondary pyridyl-alkylamines. The kinetics of some observed cleavages were measured, and a mechanism of the cleavage has been proposed.

Zinc(II) complexes derived from imidazo[1,2-a]pyridin-2-ylacetic acid (HIP-2-ac): [Zn(IP-2-ac)2(H2O)] and unexpectedly, [Zn3(IP-2-ac)6(H2O)]·11H2O

Two zinc(II) complexes based on imidazo[1,2-a]pyridin-2-ylacetate (IP-2-ac), [Zn(IP-2-ac)2(H2O)] (1) and [Zn3(IP-2-ac)6(H2O)]·11H2O (2), were synthesized and characterized by single-crystal X-ray diffraction. In both 1 and 2, zinc(II) ions are five-coordinate with N2O3 donor set, best described as a distorted trigonal-bipyramidal geometry. In 1, two IP-2-ac ligands chelate zinc(II) through a N,O donor set, whereas in 2, both bidentate and μ-bridging binding modes of IP-2-ac are observed. The crystal of 1 comprises discrete Zn(IP-2-ac)2(H2O) coordination entities combined into layers by hydrogen bonds. Inter-layer stabilization of the 3-D crystal lattice is provided by weak C–H⋯O contacts and π⋯π interactions. The structure of 2 consists of discrete trinuclear Zn3(IP-2-ac)6(H2O) coordination entities joined into crystal lattice by multiple water molecules. Compound 1 was characterized by FTIR and FT-Raman spectroscopy, and in terms of thermal stability. Furthermore, its antibacterial activity was tested against selected gram-positive, gram-negative bacteria, and Candida albicans yeast and compared with activity of previously reported [M(IP-2-ac)2(H2O)2]·2H2O (M = Co, Ni, Mn, Cd) complexes. Graphical abstract

Synthesis and antiproliferative activity of aromatic and aliphatic bis[aminomethylidene(bisphosphonic)] acids

A series of aromatic and aliphatic bis[aminomethylidene(bisphosphonic)] acids was synthesized in the reaction of triethylphosphite with isonitriles followed by hydrolysis or dealkylation. The in vitro anti-proliferative effect of all synthesized tetraphosphonic acids against MCF-7 breast cancer cells, J774E macrophages and HL-60 promyelocytic leukemia cells was determined. Three aromatic derivatives (5a, 5f and 5j) showed a similar or higher anti-proliferative activity than zoledronic acid.

Aminophosphinic Acids in a Pyridine Series, Part 2: Synthesis of 2-, 3-, and 4-Pyridyl Derivatives of 1-(Benzylamino)-methyl-H-phosphinic Acids

New 2-pyridyl, 3-pyridyl, and 4-pyridyl derivatives of 1-[N-(benzyl)amino]-methyl-H-phosphinic acid were prepared by the addition of bis(trimethylsilyl)phosphonite to the corresponding imines and subsequent methanolysis of the addition products. Treatment of the 2-pyridyl- and 1-(4-pyridyl)-1-(benzylamino)-methyl-H-phosphinic acids with aqueous mineral acids leads to cleavage and formation of the corresponding secondary amines and phosphorous acid (H 3 PO 3 ).

1D Co(II) coordination polymers based on cyclobutyl- and cyclopentyl-substituted zoledronate analogues: synthesis, structural comparison, thermal stability and magnetic properties

Two novel derivatives of zoledronic acid (1-hydroxy-2-[1-(1H-imidazol-1-yl)cyclobutyl]ethylidene-1,1-diphosphonic acid (H4cbtZol) and 1-hydroxy-2-[1-(1H-imidazol-1-yl)cyclopentyl]ethylidene-1,1-diphosphonic acid (H4cptZol)) were synthesized, crystallized from water solutions as H4cbtZol·H2O (1) and H4cptZol·4H2O (2), and characterized by single-crystal X-ray diffraction. The reactions of H4cbtZol and H4cptZol with acetate or sulphate Co(II) salts, carried out under hydrothermal conditions, afforded Co3(HcbtZol)2(H2O)6·6H2O (1a), being isomorphous with recently reported Co(II)/Ni(II) complexes based on HdmtZol3− and HcppZol3− anions, and Co3(HcptZol)2(H2O)4·2H2O (2a). Both 1a and 2a were characterized by means of X-ray crystallography, IR and NIR-Vis-UV spectroscopic methods. Furthermore, their thermal stabilities and magnetic properties were compared. Compounds 1a and 2a comprise 1D polymeric chains with crystallographically and spectroscopically distinct six-coordinated Co1 and Co2 centers, which differ in architectures. In 1a, the chains feature alternately arranged [Co2(HcbtZol)(H2O)2]2 and {Co1O6} units. The chains of 2a are constructed from dinuclear [Co2(HcptZol)(H2O)2]2 units built up from symmetry related edge-sharing {Co2O6} octahedrons, extended by corner-sharing {Co1O6} octahedrons, which results in higher rigidity imposed on trinuclear units and shorter Co2⋯Co2 and Co1⋯Co2 distances as compared to 1a. The crystal field parameters Dq, Ds, Dt and B of 798 cm−1, 450 cm−1, −75 cm−1 and 857 cm−1 for 1a and 644 cm−1, 509 cm−1, −146 cm−1 and 902 cm−1 for 2a revealed that the {Co2O6} octahedron of 2a exhibits a larger tetragonal distortion as compared to 1a, despite the nearly identical values of the tetragonality T parameter (1.07 for 2a and 1.06 for 1a). These differences are reflected in the thermal and magnetic behaviors of 1a and 2a. In particular, compound 2a is more stable than 1a, retaining thermal stability up to 208 °C. On the other hand, its dehydration is a one-stage process, accompanied by simultaneous destruction of its 1D architecture and immediate elimination and decomposition of ligands. The analysis of magnetic properties revealed the existence of competing interactions, with the predominant participation of antiferromagnetic interactions in 1a (spin-3/2 Heisenberg trimer chain) and ferromagnetic interactions in 2a (spin-1/2 Ising diamond chain).

Ultrathin film heterojunctions by combining solution processing and sublimation for ambipolar organic field-effect transistors

Ambipolar organic field-effect transistors based on binary blends of n- and p-type semiconductors frequently suffer from low or unbalanced electron and hole transport. Uncontrolled phase separation and intermixing of donor and acceptor phases in such thin film blends lead to formation of bulk heterojunctions that lack sufficient percolation paths to ensure effective transport of free charge carriers of both signs. In this work, we present a novel approach to improve the functionality of ambipolar transistors based on a common conjugated polymer, namely poly(3-hexylthiophene) (P3HT), and a small molecular naphthalene derivative (NDI-C9). We studied the correlation between the morphology and the performance of P3HT and NDI-C9 blend transistors with bulk, bilayer and structured bulk-like heterostructures. The bulk heterostructure was obtained from solution, while the bilayer and ordered bulk-like morphologies were produced by a combination of solution and vacuum deposition. The best ambipolar performance with balanced electron and hole transport was found for the bulk-like heterojunction structures of NDI-C9 evaporated onto the P3HT fiber network spin-cast from a pre-aggregated toluene solution.

Tritylamine (triphenylmethylamine) in organic synthesis; III. The synthesis of 1-aminoalkylphosphonic acids in the reaction of N-(triphenylmethyl)alkanimines with phosphorus trichloride in acetic acid or with phosphonic acid in acetic anhydride.

The reaction of phosphorus trichloride in acetic acid or phosphonic (phosphorous) acid in acetic anhydride, with N-(triphenylmethyl)alkanimines gives 1-acetylaminoalkylphosphonic acids 1a-j, which after hydrolysis give 1-aminoalkylphosphonic acids 2a-j in good yields.