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Optically passive thin films of CeO 2-TiO 2 mixed oxides with molar ratio of Ce/Ti of 0.05 were deposited by the spray pyrolysis technique (SPT) on a glass and fluorine-doped tin oxide (FTO)-coated glass substrates. Precursor solution containing cerium nitrate hexahydrate (Ce(NO 3) 2 •6H 2 O) and titanium tetraiso-propoxide (Ti(O i Pr) 4) having different volumetric proportions (0-5 vol% of Ti) in methanol were used. These films were characterized for structural, morphological, molecular, optical, electrochromic and colourimetric analysis. CeO 2-TiO 2 films deposited at 400 • C were found to be polycrystalline with cubic fluorite crystal structure. Transformation from polycrystalline to amorphous phase was observed with increasing TiO 2 content. The band centred at 539 cm −1 is assigned to Ce-O stretching vibration and the two medium intensity bands assigned to (Ti-O) and (Ti-O-Ti) stretching modes at 798 and 451 cm −1 , which confirms the mixed CeO 2 and TiO 2 phases. The band gap energy decreases (E g)f r o m 3.45 eV for pristine CeO 2 to 2.98-3.09 eV for CeO 2-TiO 2 films. The ion storage capacity (ISC) of CeO 2-TiO 2 thin film with 3 vol% Ti (Ce-Ti 3 sample) was found to be 26 mC cm −2 and electrochemical stability up to 30,000 cycles in 0.5 M LiClO 4-PC electrolyte. The optically passive behaviour of CeO 2-TiO 2 thin film is confirmed by its negligible transmission modulation (T ∼ 2.5%) upon Li + ion insertion/extraction, irrespective of the extent of Li + ion intercalation. The optical modulation of sputter deposited electrochromic WO 3 thin film was found to be enhanced from 56 to 61% with rapid increase in colouration efficiency (CE) from 42 to 231 cm 2 C −1 when CeO 2-TiO 2 is coupled as a counter electrode with WO 3 in an electrochromic device (ECD). On reduction of WO 3 thin film with CeO 2-TiO 2 as counter electrode, the CIELAB 1931 2 • colour space coordinates show the transition from colourless to the deep blue state (L * = 88.07, a * =− 2.37, b * = 24.59 and L * = 40.32, a * =− 1.16, b * =− 5.65) with steady decrease in relative lightness. Yxy and L * a * b * coordinates signify CeO 2-TiO 2 films and it also exhibits the application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion/extraction. Keywords. CeO 2-TiO 2 thin films; WO 3 thin film; counter electrode; colour analysis; electrochromism.

The reaction between methionine and enneamolybdomanganate(IV) in perchloric acid was carried out under pseudo-first-order conditions keeping large excess of methionine. The orders in oxidant and substrate were found to be unity and 0.91, respectively. The reaction proceeds with rapid formation of complex between the reactants followed by its decomposition in a rate determining step. The accelerating effect of hydrogen ions on the reaction is due to the formation of active hexaprotonated oxidant species. The product of the reaction was found to be methionine sulfoxide. The reaction involves direct two-electron transfer step without any free radical intervention. The effect of ionic strength, solvent polarity and the activation parameters were also in support of the mechanism proposed.

A clean and ecofriendly approach for the catalyst‐free synthesis of pyrido[2,3‐d]pyrimidine derivatives by one‐pot three‐component condensation of aromatic aldehyde, malononitrile and 6‐aminouracil or 6‐amino‐1,3‐dimethyluracil using glycerol–water (3:1) as green reaction media has been developed. Catalyst‐free synthesis with high to excellent yields and use of glycerol–water system as an environmentally benign reaction condition are the prominent features of this strategy. Moreover, excellent outcomes from the calculations of green chemistry metrics reveal the greenness of the protocol.