Crystal structure of trans-di­chloridobis­[N-(5,5-di­methyl-4,5-di­hydro-3H-pyrrol-2-yl-κN)acetamide]palladium(II) dihydrate

The title complex, [PdCl2(C8H14N2O)2]2H2O, was obtained by N–O bond cleavage of the oxadiazoline rings of the trans-[dichlorido-bis(2,5,5-trimethyl- 5,6,7,7a-tetrahydropyrrolo[1,2-b][1,2,4]oxadiazole-N1 )]palladium(II) complex. The palladium(II) atom exhibits an almost square-planar coordination provided by two trans-arranged chloride anions and a nitrogen atom from each of the two neutral organic ligands. In the crystal, N—HO, O—HO and O—HCl hydrogen bonds link complex molecules into double layers parallel to the bc plane.peerReviewe

Physical and chemical effects of acoustic cavitation in selected ultrasonic cleaning applications

Acoustic cavitation in a liquid medium generates several physical and chemical effects. The oscillation and collapse of cavitation bubbles, driven at low ultrasonic frequencies (e.g., 20 kHz), can generate strong shear forces, microjets, microstreaming and shockwaves. Such strong physical forces have been used in cleaning and flux improvement of ultrafiltration processes. These physical effects have also been shown to deactivate pathogens. The efficiency of deactivation of pathogens is not only dependent on ultrasonic experimental parameters, but also on the properties of the pathogens themselves. Bacteria with thick shell wall are found to be resistant to ultrasonic deactivation process. Some evidence does suggest that the chemical effects (radicals) of acoustic cavitation are also effective in deactivating pathogens. Another aspect of cleaning, namely, purification of water contaminated with organic and inorganic pollutants, has also been discussed in detail. Strong oxidising agents produced within acoustic cavitation bubbles could be used to degrade organic pollutants and convert toxic inorganic pollutants to less harmful substances. The effect of ultrasonic frequency and surface activity of solutes on the sonochemical degradation efficiency has also been discussed in this overview

Organometallic Complexes for Nonlinear Optics. 43. Quadratic Optical Nonlinearities of Dipolar Alkynylruthenium Complexes with Phenyleneethynylene/Phenylenevinylene Bridges

The syntheses of trans-[Ru(4,4\u2032-C 61CC6H4C 61CC6H4NO2)Cl(dppe)2] (19) and the systematically varied complexes trans-[Ru(4,4\u2032,4\u2032\u2032-C 61CC6H4X2C6H4Y2C6H4NO2)Cl(L2)2] [L2 ) dppe, X2 ) C 61C, Y2 ) (E)-CH)CH (12), C 61C (18); L2 ) dppe, X2 ) (E)-CH)CH, Y2 ) C 61C (14), (E)-CH)CH (16); L2 ) dppm, X2 ) C 61C, Y2 ) (E)-CH)CH (13); L2 ) dppm, X2 ) (E)-CH)CH, Y2 ) C 61C (15), (E)-CH)CH (17)] are reported, the latter being donorbridge- acceptor complexes varying in bridge composition by replacement of yne with E-ene linkages, together with their cyclic voltammetric data, linear optical, and quadratic nonlinear optical response data. RuII/III oxidation potentials increase on replacing yne linkage by E-ene linkage at the phenylene adjacent to the metal center, and on replacing dppe by dppm co-ligands. The low-energy optical absorption maxima occur in the region 20400-23300 cm-1 and are metal-to-ligand charge-transfer (MLCT) in origin; these bands undergo a blue-shift upon \u3c0-bridge lengthening by addition of phenyleneethynylene units, and on replacing E-ene linkages by yne linkages. Time-dependent density functional theory calculations on model complexes have suggested assignments for the low-energy bands. The optical spectra of selected oxidized species contain low-energy ligand-to-metal charge transfer (LMCT) bands centered in the region 9760-11800 cm-1. Quadratic molecular nonlinearities from hyper-Rayleigh scattering (HRS) studies at 1064 nm reveal an increase in the two-level-corrected 0 value on \u3c0-bridge lengthening, a trend that is not seen with values because of the blue-shift in \u3bbmax for this structural modification. Replacing yne linkages by E-ene linkage at the phenylene adjacent to the metal center or dppm co-ligand by dppe results in an increase in and 0 values. In contrast, quadratic molecular nonlinearities by HRS at 1300 nm or electric field-induced secondharmonic generation (EFISH) studies at 1907 nm do not afford clear trends

Probing Charge-Transfer Excited States in a Quasi-Nonluminescent Electron-Rich Fe(II)-Acetylide Complex by Femtosecond Optical Spectroscopy

International audienceMolecules with photoswitchable nonlinear optical (NLO) properties on the nanosecond time scale are attracting considerable attention as potential solid-state components of photonic devices, downsizeable at will, for ultrafast information encoding. In this context, we present here the study of an electron-rich Fe(II) 4-nitrophenylalkynyl complex which possesses a high hyperpolarizability in its singlet ground state and a negative (and presumably much decreased) NLO activity in its first excited MLCT state(s). On the basis of an ensemble of spectroscopic and time-resolved measurements we investigate the ultrafast dynamics for deactivation of the initially populated MLCT singlet state(s) of this particular organometallic complex, which are shown to decay into a metastable triplet state. The purported mechanism is rationalized with DFT calculations. We show that this triplet state, which should also exhibit a strongly diminished hyperpolarizability, is fully formed with a very high quantum yield within 15 ps