Probing the Influence of Novel Organometallic Copper(II) Complexes on Spinach PSII Photochemistry Using OJIP Fluorescence Transient Measurements.

Modern agricultural cultivation relies heavily on genetically modified plants that survive after exposure to herbicides that kill weeds. Despite this biotechnology, there is a growing need for new sustainable, environmentally friendly, and biodegradable herbicides. We developed a novel [CuL2]Br2 complex (L = bis{4H-1,3,5-triazino[2,1-b]benzothiazole-2-amine,4-(2-imidazole) that is active on PSII by inhibiting photosynthetic oxygen evolution on the micromolar level. [CuL2]Br2 reduces the FV of PSII fluorescence. Artificial electron donors do not rescind the effect of [CuL2]Br2. The inhibitory mechanism of [CuL2]Br2 remains unclear. To explore this mechanism, we investigated the effect of [CuL2]Br2 in the presence/absence of the well-studied inhibitor DCMU on PSII-containing membranes by OJIP Chl fluorescence transient measurements. [CuL2]Br2 has two effects on Chl fluorescence transients: (1) a substantial decrease of the Chl fluorescence intensity throughout the entire kinetics, and (2) an auxiliary "diuron-like" effect. The initial decrease dominates and is observed both with and without DCMU. In contrast, the "diuron-like" effect is small and is observed only without DCMU. We propose that [CuL2]Br2 has two binding sites for PSII with different affinities. At the high-affinity site, [CuL2]Br2 produces effects similar to PSII reaction center inhibition, while at the low-affinity site, [CuL2]Br2 produces effects identical to those of DCMU. These results are compared with other PSII-specific classes of herbicides.

Carborane-layered double hydroxide nanohybrids for potential targeted- and magnetically targeted-BNCT applications.

Carborane-intercalated layered double hydroxide nanohybrids (CB-LDH) and a magnesium ferrite (MF) supported-CB-LDH core-shell nanocomposite (CB-LDH@MF) are reported. The preparation of nanohybrids were carried out by exchanging the interlayer nitrate groups of Mg-Al-NO3-LDH with monothiol-o-carborane (SCB), 1-methyl-2-carboxyl-o-carborane (MeCB), 1-phenyl-2-carboxyl-o-carborane (PhCB) and 1,12-dicarboxyl-p-carborane (COOHCB) molecules. A magnetic core-shell nanocomposite was further prepared by supporting the COOHCB-LDH nanohybrid on MF nanoparticles. The obtained materials were characterized by means of several physical and chemical methods. Chemical compositions were determined by elemental analysis, ICP measurements and SEM-EDX data. Structural characterization was performed with powder-XRD, FTIR and magnetization measurements. Morphological analyses were conducted with electron microscopy imaging (SEM and TEM). Thermal stabilities were investigated by TGA/DTA. Carborane release from LDH layers was tested by tracing the amount of boron species transferred to the solution phase with ICP-MS measurements. The results verified that the prepared nanohybrids have the potential to be used in Boron Neutron Capture Therapy (BNCT) and magnetically targeted-BNCT applications.