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We have reported herein the synthesis of three new Cu(II) complexes of tri-and tetradentate Schiff

Sundarbans, the world's largest mangrove ecosystem, is unique and biologically diverse. A study was undertaken to track temporal succession of phytoplankton assemblages at the generic level (≥10 µm) encompassing 31 weeks of sampling (June 2010–May 2011) in Sundarbans based on microscopy and hydrological measurements. As part of this study, amplification and sequencing of type ID rbcL subunit of RuBisCO enzyme were also applied to infer chromophytic algal groups (≤10 µm size) from one of the study points. We report the presence of 43 genera of Bacillariophyta, in addition to other phytoplankton groups, based on microscopy. Phytoplankton cell abundance, which was highest in winter and spring, ranged between 300 and 27,500 cells/L during this study. Cell biovolume varied between winter of 2010 (90–35281.04 µm3) and spring-summer of 2011 (52–33962.24 µm3). Winter supported large chain forming diatoms, while spring supported small sized diatoms, followed by other algal groups in summer. The clone library approach showed dominance of Bacillariophyta-like sequences, in addition to Cryptophyta-, Haptophyta-, Pelagophyta-, and Eustigmatophyta-like sequences which were detected for the first time highlighting their importance in mangrove ecosystem. This study clearly shows that a combination of microscopy and molecular tools can improve understanding of phytoplankton assemblages in mangrove environments.

Phytoplankton forms the basis of primary production in mangrove environments. The phylogeny and diversity based on the amplification and sequencing of rbcL, the large subunit encoding the key enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase was investigated for improved understanding of the community structure and temporal trends of chromophytic eukaryotic phytoplankton assemblages in Sundarbans, the world's largest continuous mangrove. Diatoms (Bacillariophyceae) were by far the most frequently detected group in clone libraries (485 out of 525 clones), consistent with their importance as a major bloom-forming group. Other major chromophytic algal groups including Cryptophyceae, Haptophyceae, Pelagophyceae, Eustigmatophyceae, and Raphidophyceae which are important component of the assemblages were detected for the first time from Sundarbans based on rbcL approach. Many of the sequences from Sundarbans rbcL clone libraries showed identity with key bloom forming diatom genera namely Thalassiosira, Skeletonema and Nitzschia. Similarly, several rbcL sequences which were diatom-like were also detected highlighting the need to explore diatom communities from the study area. Some of the rbcL sequences detected from Sundarbans were ubiquitous in distribution showing 100% identities with uncultured rbcL sequences targeted previously from the Gulf of Mexico and California upwelling system that are geographically separated from study area. Novel rbcL lineages were also detected highlighting the need to culture and sequence phytoplankton from the ecoregion. Principal component analysis revealed that nitrate is an important variable that is associated with observed variation in phytoplankton assemblages (operational taxonomic units). This study applied molecular tools to highlight the ecological significance of diatoms, in addition to other chromophytic algal groups in Sundarbans.

Three new coordination complexes, 2{[Co (L 1 ) 2 ]ClO 4 } Á 0.5CH 3 OH (1), [Mn(L 2 ) 2 ] (2), and [Cu(HL 2 ) (L 2 )]ClO 4 Á 2H 2 O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL 1 , 2-acetylpyridine-salicyloylhydrazone, and HL 2 , 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV-Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L 1 ) 2 ] ? units and 2 consists of a neutral [Mn(L 2 ) 2 ] molecule while 3 consists of a cationic [Cu(HL 2 )(L 2 )] ? unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.

Two diorganotin(IV) complexes of general formula R2Sn[2-OC6H4CH=NDN=C(O)Ph] (R = Ph, 1; R = Me, 2) have been synthesized from the corresponding diorganotin(IV) dichloride and the Schiff base derived from salicylaldehyde and benzoyl hydrazide. The two compounds have been characterized by elemental analysis, IR and NMR (1H, 13C, 15N, 119Sn) spectra, and their structures have been confirmed by single crystal X-ray structure analysis. Crystals of complex 1 re triclinic, space group P1̄ , a = 11.1631(5), b = 13.462(2), c = 16.511(1) Å , α = 106.193(9), β = 106.379(8), γ = 94.932(8)°, Z = 4, R1 = 0.0461, wR2 = 0.0939 for 13194 unique reflections. Crystals of 2 are monoclinic, space group P21, a = 10.2073(5), b = 14.645(2), c = 10.411(3) Å, β = 92.572(9)°, Z = 4, R1 = 0.0395, wR2 = 0.0835 for 5050 unique reflections. The central tin atom of either complex adopts a distorted trigonal bipyramidal coordination with two ligand oxygen atoms in axial positions, the nitrogen atom of the ligand and two organic groups on tin occupying equatorial sites. The δ(119Sn) values for the complexes 1 and 2 are -329.2 and -150.3, respectively, thus indicating penta-coordinated tin centres.

A new diorganotin(IV) complex, Me 2 Sn[5-Br-(2-OC 6 H 4 CH=N-N=C(O)Ph)](1) has been synthesised from dimethyltin(IV) dichloride and a Schiff base derived from 5-bromosalicylaldehyde and benzoyl hydrazide. The complex has been characterised by elemental analysis, and FT-IR and NMR spectroscopies. Molecular structure has been confirmed by single-crystal X-ray diffraction analysis. Complex 1 crystallises in triclinic system, space group P-1 (no. 2) with a = 7.562 (6), b = 9.980(8), c = 11.899(8) Å; α = 81.08(6) • , β = 72.71(5) • , γ = 79.64(6) • ; Z = 2. The ligand N -(5-bromo-2-hydroxybenzylidene)benzoylhydrazone (H 2 L) coordinates to the metal centre in enolate form via the phenolic O, imino N and enolic O atoms. The central tin atom is in distorted trigonal bipyramidal geometry with two oxygen atoms of the ligand in axial positions, while the imino nitrogen atom of the ligand and two methyl groups on tin occupy the equatorial sites.

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