Bioprospecting Fluorescent Plant Growth Regulators from Arabidopsis to Vegetable Crops.

The phytohormone auxin is involved in almost every process of a plant's life, from germination to plant development. Nowadays, auxin research connects synthetic chemistry, plant biology and computational chemistry in order to develop innovative and safe compounds to be used in sustainable agricultural practice. In this framework, we developed new fluorescent compounds, ethanolammonium p-aminobenzoate (HEA-pABA) and p-nitrobenzoate (HEA-pNBA), and investigated their auxin-like behavior on two main commercial vegetables cultivated in Europe, cucumber (Cucumis sativus) and tomato (Solanumlycopersicum), in comparison to the model plant Arabidopsis (Arabidopsis thaliana). Moreover, the binding modes and affinities of two organic salts in relation to the natural auxin indole-3-acetic acid (IAA) into TIR1 auxin receptor were investigated by computational approaches (homology modeling and molecular docking). Both experimental and theoretical results highlight HEA-pABA as a fluorescent compound with auxin-like activity both in Arabidopsis and the commercial cucumber and tomato. Therefore, alkanolammonium benzoates have a great potential as promising sustainable plant growth stimulators to be efficiently used in vegetable crops.

Crystal Engineering of Schiff Base Zn(II) and Cd(II) Homo- and Zn(II)M(II) (M = Mn or Cd) Heterometallic Coordination Polymers and Their Ability to Accommodate Solvent Guest Molecules.

Based on solvothermal synthesis, self-assembly of the heptadentate 2,6-diacetylpyridine bis(nicotinoylhydrazone) Schiff base ligand (H2L) and Zn(II) and/or Cd(II) salts has led to the formation of three homometallic [CdL]n (1), {[CdL]∙0.5dmf∙H2O}n (2) and {[ZnL]∙0.5dmf∙1.5H2O}n (3), as well as two heterometallic {[Zn0.75Cd1.25L2]∙dmf∙0.5H2O}n (4) and {[MnZnL2]∙dmf∙3H2O}n coordination polymers. Compound 1 represents a 1D chain, whereas 2-5 are isostructural and isomorphous two-dimensional structures. The entire series was characterized by IR spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction and emission measurements. 2D coordination polymers accommodate water and dmf molecules in their cage-shaped interlayer spaces, which are released when the samples are heated. Thus, three solvated crystals were degassed at two temperatures and their photoluminescent and adsorption-desorption properties were recorded in order to validate this assumption. Solvent-free samples reveal an increase in volume pore, adsorption specific surface area and photoluminescence with regard to synthesized crystals.

p-Aminobenzoate Organic Salts as Potential Plant Growth Regulators for Tomatoes.

The discovery of environmentally friendly and inexpensive plant growth regulators (PGRs) for agronomically important crops is a necessity and must be considered a priority worldwide. This study provides the synthesis, structure determination and the biological evaluation of two binary organic salts as potential PGRs. New compounds have dual biological activity and are based on natural metabolite p-aminobenzoic acid (pABAH) and different alkanolamines. Studied compounds exhibit hydrogen-bonded 3D supramolecular architectures with different crystal packing due to the formation of one homosynthon and various heterosynthons. The biological profile of new compounds was investigated in laboratory and greenhouse on Solanum lycopersicum L., revealing the efficiency in promoting plant rooting and plant productivity. The results may have a positive impact on agricultural economics, developing new sustainable PGRs for tomatoes.

X-ray Structure Elucidation of a Pt-Metalloporphyrin and Its Application for Obtaining Sensitive AuNPs-Plasmonic Hybrids Capable of Detecting Triiodide Anions.

The development of UV⁻vis spectrophotometric methods based on metalloporphyrins for fast, highly sensitive and selective anion detection, which avoids several of the practical challenges associated with other detection methods, is of tremendous importance in analytical chemistry. In this study, we focused on achieving a selective optical sensor for triiodide ion detection in traces based on a novel hybrid material comprised of Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) and gold nanoparticles (AuNPs). This sensor has high relevance in medical physiological tests. The structure of PtTMeOPP was investigated by single crystal X-ray diffraction in order to understand the metal surroundings and the molecule conformation and to assess if it qualifies as a potential sensitive material. It was proven that the Pt-porphyrin generated 1D H-bond supramolecular chains due to the weak C-H···O intermolecular hydrogen bonding. The presence of ordered voids in the crystal encouraged us to use PtTMeOPP as the sensing material for triiodide ion and to enhance its potential in a novel AuNPs/PtTMeOPP hybrid by the synergistic effects provided by the plasmonic gold nanoparticles. The spectrophotometric sensor is characterized by a detection limit of 1.5 × 10-9 M triiodide ion concentration and a remarkable confidence coefficient of 99.98%.

Bis[2-(hy-droxy-imino)-cyclo-hexan-1-one oximato-κ(2) N,N']copper(II).

In the title compound, [Cu(C6H9N2O2)2], the Cu(II) atom is located on an inversion center and has a square-planar environment. Two 2-(hy-droxy-imino)-cyclo-hexan-1-one oxim-ate monoanions chelate to the Cu(II) atom and the Cu-N distances are 1.920 (3) and 1.930 (3) Å. There are two short intra-molecular O-H⋯O hydrogen bonds between the ligands. The complex mol-ecules stack into columns extended along the c axis, with a Cu⋯Cu distance between adjacent mol-ecules of 3.3060 (3) Å.

Di-aqua-bis-(pyridine-2-carboxyl-ato-κ(2) N,O)zinc di-methyl-formamide hemisolvate.

In the title compound, [Zn(C6H4NO2)2(H2O)2]·0.5C3H7NO, the Zn(II) ion is coordinated in a distorted octa-hedral N2O4 environment by two N,O-chelating pyridine-2-carboxyl-ate ligands and two cis water mol-ecules. The chelating pyridine-2-carboxyl-ate ligands create two five-membered Zn/N/C/C/O rings, which form a dihedral angle of 86.4 (2)°. In the crystal, O-H⋯O hydrogen bonds link the complex mol-ecules into a two-dimensional network parallel to (100). The di-methyl-formamide solvent mol-ecule is disordered about a twofold rotation axis.

A one-dimensional coordination polymer based on Cu3-oximato metallacrowns bridged by benzene-1,4-dicarboxylato ligands: structure and magnetic properties.

A one-dimensional linear coordination polymer {[Cu3(µ3-OH)(2-pyao)3(bdc)]·6(H2O)}n () composed of trinuclear [Cu3(µ3-OH)(2-pyao)3](2+) metallacrown cores bridged by bis-carboxylato linkers has been obtained by treatment of copper(ii) fluoride with pyridine-2-aldoxime (2-pyaoH) ligand and benzene-1,4-dicarboxylic acid (H2bdc). Magnetic susceptibility measurements show strong antiferromagnetic interactions between Cu(ii) centers within the trinuclear metallacrown core with J = -430 cm(-1).

Two Zn(II) mononuclear coordination compounds with pyridinedicarboxylate and auxiliary N-(pyridin-4-ylmethylidene)hydroxylamine ligands.

Two new mononuclear coordination compounds, bis{4-[(hydroxyimino)methyl]pyridinium} diaquabis(pyridine-2,5-dicarboxylato-κ(2)N,O(2))zincate(II), (C6H7N2O)2[Zn(C7H3NO4)2(H2O)2], (1), and (pyridine-2,6-dicarboxylato-κ(3)O(2),N,O(6))bis[N-(pyridin-4-ylmethylidene-κN)hydroxylamine]zinc(II), [Zn(C7H3NO4)(C6H6N2O)2], (2), have been synthesized and characterized by single-crystal X-ray diffractometry. The centrosymmetric Zn(II) cation in (1) is octahedrally coordinated by two chelating pyridine-2,5-dicarboxylate ligands and by two water molecules in a distorted octahedral geometry. In (2), the Zn(II) cation is coordinated by a tridentate pyridine-2,6-dicarboxylate dianion and by two N-(pyridin-4-ylmethylidene)hydroxylamine molecules in a distorted C2-symmetric trigonal bipyramidal coordination geometry.