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A new Ce(III) complex of 5-aminoisophthalic acid (H 2 aip), [Ce(CH 3 COO)(aip)(H 2 O) 2 ]·H 2 O, has been prepared by single gel diffusion technique at room temperature using sodium metasilicate. The gel-grown crystals were characterised by CHN analysis, thermogravimetry, FT-IR and UV- Visible spectral studies. The single crystal X- ray diffraction studies reveal that the title compound crystallizes in monoclinic space group P 2 1 /c. CeO 9 polyhedra have distorted tricapped trigonal prism geometry and form edge sharing dimers. The adjacent dimers are connected by aip 2− in different directions and generate a three dimensional network structure with hydrophilic channels. The luminescent behaviour of the complex and the ligand were also investigated and the complex shows blue shifted emission. [ABSTRACT FROM AUTHOR]

Seasonal variability in the vertical distribution of ozone over a tropical station, Thumba (8.5°N, 76.9°E) is investigated using nine-years (2011–2019) of ECC ozonesonde data obtained as part of Tropical Tropopause Dynamics (TTD) campaigns. Ozone exhibits a clear annual variation in the lower troposphere (0–2 km) with winter maximum (49.2 ± 3.6 ppbv) and summer monsoon minimum (21.9 ± 0.7 ppbv). In the middle (2–10 km) and upper (11–17 km) troposphere, ozone is maximum in pre-monsoon and minimum in summer monsoon. Ozone in the lower stratosphere exhibits a clear annual variation with summer monsoon maximum and winter minimum in tandem with the temperature cycle. The relative standard deviation (RSD) of ozone computed at different altitudes exhibits large intra-seasonal variability in the troposphere (~20–30%) compared to the stratosphere (~5%) and is significantly high close to the surface and in the tropical tropopause layer (TTL) (≥30%). Maximum RSD is observed during summer monsoon (June–September) in the upper troposphere (~50%) close to cold point tropopause (CPT). RSD in ozone and temperature profiles show a sharp peak immediately above the CPT in all the seasons, coinciding with the altitude of maximum wind shear. Tropospheric ozone shows an in phase relationship with temperature and is opposite in phase with water vapour. A significant negative correlation is observed between ozone and water vapour in the 2–5 km altitude region. Long-range transport and local convection contribute substantially to the observed variability in tropospheric ozone. The tropospheric column ozone shows a semi-annual variation with maximum contribution to the total columnar ozone during pre-monsoon (~16%) and minimum during summer monsoon (~8%). Mid-tropospheric ozone contributes more to the tropospheric column ozone (40–60%) compared to lower and upper tropospheric ozone. Tropospheric column ozone exhibits a similar seasonality as that of its precursors like NO 2 , CO and CH 4. • Ozone distributions shows high intraseasonal variability near the CPT. • Local convection and long-range transport determine tropospheric ozone variability. • Significant contribution to the tropospheric column ozone is from the mid-troposphere. [ABSTRACT FROM AUTHOR]

Single crystals of a new coordination polymer of lead-benzilate, C 28 H 21 O 6 Pb·C 2 H 5 OH have been successfully grown by gel diffusion technique at room temperature. The colourless single crystals were obtained within a week. The crystal structure was elucidated using single crystal X-ray diffraction studies. The compound possesses a polymeric structure constructed from edge sharing PbO 6 polyhedra. Single crystal X-ray diffraction analysis showed that the compound crystallizes in triclinic space group P -1. The grown crystals were further characterized by elemental analysis, FT-IR, UV–Visible and thermogravimetric analysis. The photoluminescent properties of the complex and the ligand were also investigated. [ABSTRACT FROM AUTHOR]

Proposed photocatalytic dye degradation mechanism by means of the Cd complex, {[Cd(TDC)(Nic)(H 2 O)].3H 2 O} n (CTDCN) [H 2 TDC = thiophene-2,5-dicarboxylic acid and Nic = nicotinamide] [Display omitted] • A new coordination polymer of Cd(II) with thiophene-2,5-dicarboxylic acid and nicotinamide was prepared. • In the crystal structure, the Cd-thiophene-2,5-dicarboxylate units extend to form 1D chain. • The 1D chains are further interconnected by nicotinamide molecules to form ladder-like structure. • Photocatalytic dye degradation studies were conducted using methylene blue in sunlight and a degradation of 33% was observed. A new coordination polymer of Cd(II) of formula {[Cd(TDC)(Nic)(H 2 O)]·3H 2 O} n (H 2 TDC = thiophene-2,5-dicarboxylic acid and Nic = nicotinamide) has been prepared by gel diffusion method. Various analytical techniques such as elemental analysis, single crystal X-ray diffraction, thermogravimetry, FT-IR and UV–visible spectroscopy were used for the characterization of the compound. In the crystal structure, the Cd-thiophene-2,5-dicarboxylate units extend to form 1D chains. Interconnections of 1D chains by the carbonyl oxygen and nitrogen from the pyridine ring of nicotinamide molecules provide a ladder-like structure that possesses 1D channels. Extensive hydrogen bonding results in the formation of a layered structure. Photocatalytic dye degradation property of the coordination polymer was investigated by using methylene blue under sunlight. Photoluminescence and thermal studies were also carried out. [ABSTRACT FROM AUTHOR]

Balloon-borne cryogenic frost-point hygrometer (CFH) observations conducted over three stations Trivandrum, Hyderabad and Kolkata in the Indian region during the period 2014–2017 are used to study the influence of deep convection and monsoon dynamics on the distribution of water vapour in the upper troposphere and lower stratosphere (UTLS) and to quantify the amount of water vapour transported to the lower stratosphere (LS) during summer-monsoon (June to September). In summer monsoon season, CFH observations show a water vapour enhancement of ~40–250% in the upper troposphere (UT) and 0.5–1 ppmv (10–40%) in the LS compared to pre-monsoon. In this season, the spatial pattern of Microwave Limb Sounder (MLS) derived water vapour mixing ratio (WVMR) at 100 hPa peaks north of the deep convection core over the head Bay of Bengal (BoB). In the LS, the water vapour maximum shows a south westward shift with altitude in accordance with the anticyclonic circulation flow. The maximum altitude of deep convective cloud top increases north eastward in accordance with the peak in tropical easterly jet (TEJ) causing the altitudinal shift in water vapour enhancement in the UT. The probability of dehydration (WVMR<3 ppmv) maximizes west of the deep convective core over Head BoB. During summer-monsoon, the day-to-day variability of water vapour in the tropical tropopause layer (TTL) is mainly controlled by the dehydration of air due to freeze drying (temperature dependent) and rehydration due to recurrent overshooting deep convections. Direct injection of water vapour into the LS region is probable when the tropopause is relatively warm (>192 K). • Insitu observations of effect of monsoon dynamics and deep convection on water vapour in the UTLS during summer monsoon • Water vapour enhancement of ~40–250% in the UT and 10–40% in the LS in summer monsoon compared to pre-monsoon • The water vapour maximum shows a south westward shift with altitude in the LS region • The maximum altitude of deep convective cloud top increases north eastward over Indian region similar to the peak in TEJ [ABSTRACT FROM AUTHOR]

This paper deals with the temporal changes in the altitude distribution of tropospheric ozone (O 3) based on the measurements by balloon-borne O 3 -sondes during 2011–2014, conducted at the tropical, coastal site Thiruvananthapuram on the south west coast of India. This is the first study from this region addressing the highly dynamic nature of tropospheric O 3 profiles (in terms of their vertical structure and short-term changes) and attempting to categorise them based on 121 in-situ measured O 3 profiles. The tropospheric O 3 profiles could be categorised into four major groups namely (i) those with steady O 3 mixing ratio (ii) with increasing mixing ratio, (iii) with mid-tropospheric enhancement and (iv) with multiple layers/laminar nature. The causative mechanisms of these different categories were examined. The observed differences in the tropospheric O 3 distribution are attributed to meteorological conditions in particular the synoptic scale systems, long range transport, intrusion from stratosphere and photochemistry, most importantly, the effect of water vapour content. Water vapour and O 3 showed complex dependence with positive and negative association depending on the precursor levels and availability of water vapour. The altitudinal changes in O 3 also exhibited close association with those of potential temperature and equivalent potential temperature. An analysis of the seasonal characteristics of vertical distribution of tropospheric O 3 also carried out along with the altitude-dependent seasonal behaviour. In general, the total column O 3 estimated by the integration of O 3 -sonde retrieved profiles differed by about ±10% with those retrieved by satellite-based measurements. The TCO contributes to about 16% (34 DU) of the total column O 3 , with minimum of 9% in October and maximum of 27% on March. In general, the OMI retrievals under-estimates the O 3 -sonde derived TCO by 5–10 DU in all the seasons. • Dynamic nature of tropospheric O 3 profiles observations based on O 3 -sonde. • Dependence of O 3 on water vapour shows positive and negative correlation. • Amount of water vapour and precursors decide nature of water vapour dependence of O 3. • The seasonal variation of tropospheric O 3 is altitude-dependent. • Tropospheric column O 3 contributes about 16% of the total column O 3. [ABSTRACT FROM AUTHOR]