The current status and distribution of the rare and threatened dragonfly Onychogomphus macrodon (Selys, 1887) was studied in Turkey 2006-2009. Despite an intensive search for the species, it was ...found only at one locality in the middle course of the Ceyhan river. Other localities in Turkey, from where the species has been reported in the literature which could not be confirmed. The habitat preference of the species is described and observations on the behaviour of both sexes were made. Some morphological details are described and notes on the colour are given. Literature records are summarised and reasons for the decline of this species are discussed.
The Indian River Lagoon (IRL) is an Estuary of National Significance with numerous documented harmful algal blooms (HABs). Light microscopy is routinely used to identify IRL HABs, including ...Pseudo-nitzschia spp. and Pyrodimiim bahamense. Smaller-sized nanoplankton, such as the brown tide alga, Aiireoumbra lagunensis, can be difficult to definitively identity, but a network for enhanced monitoring was initiated in the IRL after large nanoplankton blooms in 2011, 2012, and 2013. We present monitoring results from samples collected between 2015-2020 and examined for HAB abundance using microscopy. We also used immunofluorescence flow cytometry and a newly developed qPCR approach to confirm the presence of A. lagunensis during bloom and non-bloom periods. Blooms of A. lagunensis (>200 million cells/L) were observed in all years and across seasons. In contrast, P. bahamense displayed a strong seasonal pattern with blooms (>100,000 cells/L) generally developing in early summer and subsiding in autumn. Pseudo-nitzschia spp. were broadly distributed and blooms (>100,000 cells/L) were more sporadic. In summer 2020, a bloom of a nano-sized cyanobacterium was first detected in the northern IRL, expanded to other subbasins, and persisted into December. It is not yet clear if this alga occurred in the IRL prior to this event, but genetic and microscopic analyses suggest it represents a novel taxon. While high biomass blooms of nano-sized algae have been prevalent over the last decade, statistical analyses suggest that environmental conditions preceding or coinciding with these large-scale blooms have varied and may be event-driven. These blooms, however, may act as overriding controls that influence seasonal occurrences of other phytoplankton taxa. Sustained and enhanced monitoring coupled with physiology/life cycle studies for IRL HABs will help provide further insight into mechanisms underlying likely patterns of species succession over seasonal to interannual timescales.
A series of molecular materials that are structurally similar to the Ni
II
macrocycle Ni(cyclam)
2+
(cyclam = 1,4,8,11-tetraazacyclotetradecane) have been used as electrocatalysts for the reduction ...of CO
2
at a mercury pool working electrode in aqueous solution. At pH 5, with an applied potential of −0.96 V
vs.
NHE (overpotential of −0.55 V), the complexes are highly efficient, having both high rate constants and Faradaic efficiencies (F.E.s) for the selective reduction of CO
2
to CO. When the pH is below the p
K
a
(pH < 2) of the Ni(H) species (p
K
a
s: 0.5-2), the F.E.s are still high but product selectivity changes to yield predominantly H
2
from the reduction of water. At least two of the complexes investigated are better electrocatalysts than Ni(cyclam)
2+
, probably due to: (i) surface geometries that are suitable for adsorption onto the mercury electrode surface, and (ii) electronic effects of methyl groups or cyclohexane rings on the cyclam backbone. Mechanistic studies by pulse radiolysis show evidence of Ni(CO
2
) adducts for two of the catalysts, with
K
CO
2
∼ 10 M
−1
for the reaction of Ni
I
with CO
2
in aqueous solution.
Ni(
ii
) electrocatalysts are used for the selective reduction of CO
2
to CO in aqueous solution at a Hg pool electrode.
A series of molecular materials that are structurally similar to the Ni super(II) macrocycle Ni(cyclam) super(2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been used as electrocatalysts for ...the reduction of CO sub(2) at a mercury pool working electrode in aqueous solution. At pH 5, with an applied potential of -0.96 V vs. NHE (overpotential of -0.55 V), the complexes are highly efficient, having both high rate constants and Faradaic efficiencies (F.E.s) for the selective reduction of CO sub(2) to CO. When the pH is below the pK sub(a) (pH < 2) of the Ni(H) species (pK sub(a)s: 0.5-2), the F.E.s are still high but product selectivity changes to yield predominantly H sub(2) from the reduction of water. At least two of the complexes investigated are better electrocatalysts than Ni(cyclam) super(2+), probably due to: (i) surface geometries that are suitable for adsorption onto the mercury electrode surface, and (ii) electronic effects of methyl groups or cyclohexane rings on the cyclam backbone. Mechanistic studies by pulse radiolysis show evidence of Ni(CO sub(2)) adducts for two of the catalysts, with K sub(C)O sub(2) similar to 10 M super(-1) for the reaction of Ni super(I) with CO sub(2) in aqueous solution.
Iridium complexes containing the large bite angle bisphosphine ligand xantphos have been synthesized and their reactivity studied. Several of these complexes are the first reported Ir(xantphos) ...systems to be characterized by X-ray diffraction. Variable-temperature NMR spectroscopic studies of IrI(CO)2(xantphos) (1-I) and Ir(COEt)(CO)2(xantphos) (8) show two separate dynamic processes in which the phosphorus donors and the backbone methyl groups of the xantphos ligand are exchanged. The addition of parahydrogen (p-H2) to 1-I leads to the formation of two dihydride isomers including one in which both hydride ligands are trans to the phosphorus donors, suggestive of an Ir(I) xantphos intermediate with the ligand chelated in a trans-spanning fashion (2b). The bromide and chloride Ir(I) analogues (1-Br and 1-Cl) also form this isomer upon reaction with parahydrogen, with 1-Cl yielding only this dihydride species. The trihydride complex IrH3(CO)(xantphos) (7) has been prepared, and its exchange with free hydrogen at elevated temperature is confirmed by reaction with p-H2. The hydride complexes IrH(CO)2(xantphos) (6) and IrH3(CO)(xantphos) (7), as well as the propionyl complex 8, are modest catalysts for the hydroformylation of 1-hexene and styrene under mild conditions. The addition of p-H2 to 8 permits direct observation of the propionyl dihydride species IrH2(COEt)(CO)(xantphos) (9) under both thermal and photolytic conditions, as well as unusual but weak polarization of the aldehydic proton of the propanal product that forms upon reductive elimination from 9.
Photocatalytic CO
2
reduction has been studied for two dyads with porphyrin covalently attached to rhenium tricarbonyl bipyridine moieties, and on separate components consisting of Re(CO)
3
...(Picoline)Bpy
+
and either zinc porphyrin or zinc chlorin. TONs decrease in the order: zinc porphyrin + Re > long spacer dyad > zinc chlorin + Re > short spacer dyad.
CO
2
is reduced to CO with visible light using zinc porphyrins as photosensitisers and rhenium complexes as catalysts: catalysis is more effective with separate monomers than with dyads.
Photocatalytic CO sub(2) reduction has been studied for two dyads with porphyrin covalently attached to rhenium tricarbonyl bipyridine moieties, and on separate components consisting of Re(CO) ...sub(3)(Picoline)Bpy super(+) and either zinc porphyrin or zinc chlorin. TONs decrease in the order: zinc porphyrin + Re > long spacer dyad > zinc chlorin + Re > short spacer dyad.
Four new Pt(ii) terpyridyl acetylide complexes are reported which possess either a viologen or nicotinamide unit attached as an electron acceptor via the benzylic carbon of the tolyl-terpyridine ...ligand. Specifically, the donor-chromophore-acceptor (D-C-A) triads prepared are Pt(ttpy-MV)Cidentical withC-C6H4-NH-CO-C6H2(OMe)3(PF6)3 1, where ttpy-MV = 4prime or minute-(4-methyl-4,4prime or minute-bipyridin-ylmethyl-phenyl)-2,2prime or minute; 6prime or minute,2double primeterpyridine and Cidentical withC-C6H4-NH-CO-C6H2(OMe)3 = N-(4-ethynylphenyl)-3,4,5-trimethoxybenzamide and Pt(ttpy-Nd)Cidentical withC-C6H4-NH-CO-C6H2(OMe)3(PF6)2 2, where ttpy-Nd = 4prime or minute-(3-carboxamide-pyridin-ylmethyl-phenyl)-2,2prime or minute; 6prime or minute,2double primeterpyridine. The related chromophore-acceptor (C-A) dyads, Pt(ttpy-MV)Cidentical withCPh(PF6)3 3, where Cidentical withCPh = phenylacetylide and Pt(ttpy-Nd)Cidentical withCPh(PF6)2 4, were also prepared. The syntheses of the above compounds are achieved by the reaction of a prepared cuprous phenylacetylide compound with the appropriate platinum terpyridyl chloride complex. This change from the CuI-catalyzed acetylide coordination, which requires basic conditions, results from the observed sensitivity of the pyridinium type acceptors to base. While the parent chromophore, Pt(ttpy)Cidentical withCPhPF6 5, where ttpy = 4prime or minute-p-tolyl-2,2prime or minute; 6prime or minute,2double primeterpyridine, is brightly emissive in fluid solution, both of the aforementioned D-C-A triads 1 and 2 are nonemissive at room temperature. Of the related C-A dyads, 4 is emissive and 3 is very weakly emissive. Transient absorption studies reveal that the nicotinamide acceptor does not function as an oxidative quencher of the excited state. In contrast, the viologen acceptor appears to function as an oxidative quencher.
The (benzophenone imine)platinum(II) compounds trans-PtCl2(Ph2CNH)(RR‘SO) R, R‘ = Me, Me (2); n-Pr, n-Pr (3); (CH2)4 (4); Me, Ph (5); Me, p-MeC6H4 (6) were prepared by the reaction of Ph2CNH with ...KPtCl3(RR‘SO), obtained in situ from K2PtCl4 and the corresponding sulfoxide, giving 2−6 as well as cis-PtCl2(Ph2CNH)2 (1) as a minor product. The complexes were characterized by 1H, 13C, and 195Pt NMR and IR spectroscopy, electrospray ionization mass spectrometry, and C, H, and N elemental analysis. The X-ray crystallography of 1 enables confirmation of the cis configuration of the complex, while in 2 and 4·1/2CHCl3, the imine and sulfoxide ligands are mutually trans. The solid-state structure of 4·1/2CHCl3 consists of two dimeric Pt moieties representing a rather weak Pt···Pt interaction. The dimeric architecture of 4·1/2CHCl3 is enhanced by the hydrogen bonding between imine H atoms and O atoms. The orthometalation of 1 and 2−6 proceeds both in the solid phase and in a toluene suspension, leading to the formation of PtCl{Ph(C6H4)CNH}(Ph2CNH) (7) and PtCl{Ph(C6H4)CNH}(RR‘SO) (8−12), respectively, isolated in nearly quantitative yields. Complexes 8−12 are emissive at room temperature both in solution ( ∼535 nm) and in the solid state ( 560−610 nm), with excited-state lifetimes of ca. 300−600 ns, representing a new family of PtII-based luminescent complexes. Compounds 8 and 10 have been characterized by X-ray analysis, confirming the square-planar coordination geometry of the metal center with the almost planar platinacycles. In 8, the asymmetric unit contains two independent Pt molecules, while in 10, it includes four Pt molecules linked by the intermolecular hydrogen-bonding network between the NH group and Cl atoms.
