Ligand-Directed Synthesis of a Self-Organized Chloro-Bridged Cubic Pd(II) Cage Showing Selective Encapsulation of Phenols.

The synthesis and guest recognition properties of a neutral Pd24-cubic cage, [{Pd3(NiPr)3PO}8(µ2-Cl)24] 1 are reported. The formation of the cubical assembly takes place by an exclusive one-pot ligand-assisted pathway directed by an oximido linker. The initial coordination of the oximido ligand pre-organizes the [Pd3(NiPr)3PO]3+ polyhedral building units into a tetrameric intermediate, which then transforms into an oximido-tethered tetrahedral assembly and to the cubical cage 1 in the presence of chloride ions. In the absence of the directing oximido linker, no cage formation was observed, and the Pd6-precursor was found to undergo self-condensation, giving rise to a new pentameric polyhedral cluster, [Pd5{(NiPr)3PO}2(OAc)2(OH)2] 2. The central cavity of the cube has been probed for guest encapsulation studies, which shows a high binding with phenolic guest molecules with association constants of the order of 104-105 M-1. The favorable formation of host-guest complexes was attributed to the strong hydrogen bonding interactions between the host and guest functional groups.

Visualization of domain structure and piezoelectric energy harvesting in a ferroelectric metal-ligand cage.

The ferroelectric behaviour of an octahedral cage [[Ni6(H2O)12(TPTA)8]·(NO3)12·36H2O] (1) exhibiting high remnant polarization of 25.31 µC cm-2 is discovered. For the first time, clear domain structures and the characteristic electromechanical responses are demonstrated using piezoresponsive force microscopy for a thin film of 1. Owing to its mechanical energy conversion capability, polymer composites of 1 were employed as efficient piezoelectric nanogenerators.

Impact of highway construction on water bodies: a geospatial assessment.

India has witnessed a massive infrastructure boom in the past few years. One of such projects is National Highway-7 (NH-7), a North-South highway connecting Kanyakumari, Tamil Nadu, to Varanasi, Uttar Pradesh, traversing many water bodies. The present study aims to assess the pre- and post-construction impact due to existing, new and widened NH-7 on the physical status of the water bodies, using remote sensing techniques. Satellite images spanning 22 years were procured and analysed for change detection in land use and land cover within the waterbodies. The study indicates that construction activities have led to transformation within the water bodies regarding reduction in area and inter-changing of land use and land cover classes, in turn leading to siltation and reduction of recharge.

A multi-temporal analysis for change assessment and estimation of algal bloom in Sambhar Lake, Rajasthan, India.

Sambhar Lake in Rajasthan, India is the major inland salt water lake producing salt for centuries. The present study addresses the monitoring changes in and around the lake and its consequent effect on the lake water ecology. For this, satellite images of the years 1976, 1981, 1997, and 2013 are analyzed for land use land cover classes. Significant reduction in the water body is observed in contrast with the increase in salt pan around the periphery of lake and wetland classes. Further, the extent of water body and algae in the lake are delineated as per normalized difference water index and normalized difference vegetation index. Rainfall data do not indicate any major change in the pattern, but drastic decrease in the extent of water body and significant increase in algal bloom are serious concerns for the lake's existence. This may be due to surrounding anthropogenic activities and construction of check dams and anicuts in the lake catchment which curtail the runoff into the lake and provide favorable growth of algae. Sambhar Lake, being declared as a wetland according to the Ramsar Convention, is necessary to protect and conserve the ecological importance of the lake through sustainable planning and management.

Object-based image analysis for the impact of sewage pollution in Malad Creek, Mumbai, India.

Today, object-based image analysis provides an option for integrating spatial information beyond conventional pixel-based classifications for high-resolution imagery. Due to its rare applicability in pollution assessment, an attempt has been made to assess the spatial extent of sewage pollution in Malad Creek, Mumbai, India. Based on multiresolution segmentation of an IRS P6 (LISS IV) image and the Normalized Difference Turbidity Index (NDTI), the various water quality regions in the creek were classified. The existing literature implies that the reflectance of turbid water is similar to that of bare soil which gives positive NDTI values. In contrast to this, negative values of NDTI are observed in the present study due to the presence of organic matter which absorbs light and imparts turbidity, which is supported by the significant correlation between NDTI and turbidity. A strong relationship is observed between turbidity and water quality parameters, implying the impact of organic matter through discharges of sewage in the creek. Based on the classified regions and the water quality parameters, the extent of pollution was ranked as high, moderate, low and least. The methodology developed in the present study was successfully applied on an IKONOS image for the same study area but a different time frame. The approach will help in impact assessment of sewage pollution and its spatial extent in other water bodies.