Computational Solar Energy -- Ensemble Learning Methods for Prediction of Solar Power Generation based on Meteorological Parameters in Eastern India

The challenges in applications of solar energy lies in its intermittency and dependency on meteorological parameters such as; solar radiation, ambient temperature, rainfall, wind-speed etc., and many other physical parameters like dust accumulation etc. Hence, it is important to estimate the amount of solar photovoltaic (PV) power generation for a specific geographical location. Machine learning (ML) models have gained importance and are widely used for prediction of solar power plant performance. In this paper, the impact of weather parameters on solar PV power generation is estimated by several Ensemble ML (EML) models like Bagging, Boosting, Stacking, and Voting for the first time. The performance of chosen ML algorithms is validated by field dataset of a 10kWp solar PV power plant in Eastern India region. Furthermore, a complete test-bed framework has been designed for data mining as well as to select appropriate learning models. It also supports feature selection and reduction for dataset to reduce space and time complexity of the learning models. The results demonstrate greater prediction accuracy of around 96% for Stacking and Voting EML models. The proposed work is a generalized one and can be very useful for predicting the performance of large-scale solar PV power plants also.Comment: Accepted in Renewable Energy Focus (Elsevier

Recent development of alkali metal complex promoted iso-selective ring opening polymerization of rac-Lactide

Polyesters especially polylactide (PLA) are one of the most important and extensively studied biodegradable polymers for their use in medicine, agriculture, packaging, and drug delivery. Importantly, these polymers can be formed by the ring opening polymerization (ROP) of lactide by carefully designed metal complexes that can act as catalysts for such reactions have emerged as useful tools to achieve this goal. In recent years, alkali metal-based organometallic complexes have appeared as an alternative to transition metal and rare earth metals catalysts for the ROP of rac-LA systems. This strategy is advantageous because it obviates the need for pre-generated toxic metal precursors. This review highlights the progress of alkali metal-based catalysis for the ROP of rac-LA that come out with a critical assessment of the futuristic research, spotlight the major developments achieved in the past few years, and provides an overview of the challenges and opportunities

Alkali and Alkaline Earth Metal Complexes as Versatile Catalysts for Ring‐Opening Polymerization of Cyclic Esters

Biodegradable polyesters such as poly(ϵ-caprolactone) (PCL) and poly(lactic acid) (PLA) have been considered for use in several areas, such as drug delivery devices, sutures, tissue engineering, and GBR membranes, due to its bio-renewability, biodegradability, and biocompatibility. Several synthetic techniques for the preparation of polyesters have been reported in the literature, amongst which the ring-opening polymerization (ROP) of cyclic esters is the most efficient. A convenient approach to access iso-selective PLAs is polymerization of racemic lactide (rac-LA), which shows excellent stereoregularity without the need for costly chiral auxiliaries or ligands. In this personal account, we review a series of methods that have been practiced to the synthesis of biodegradable polyesters from various cyclic monomers using alkali and alkaline earth metal complexes as efficient catalysts

Imidazolin-2-iminato ligand supported organozinc complex as Catalyst for Hydroboration of Organic Nitriles

The reaction of diethylzinc with imidazolin-2-imines (ImRNH, R = Dipp (2,6-diisopropylphenyl), Mes (2,4,6-trimethylphenyl), tBu (tert-butyl) afforded the corresponding dimeric zinc(II) imidazolin-2-iminato complexes [{(ImRN)Zn(CH2CH3)}2] (R = Dipp, 1a; R = Mes, 1b; R = tBu, 1c). The zinc complexes were characterised using spectroscopic techniques and the molecular structure of complex 1b was established by single-crystal x-ray diffraction analysis. Complex 1c was used as a catalyst for the chemo-selective hydroboration of organic nitriles with pinacolborane (HBpin) at ambient temperature to obtain diborylamines of a broad substrate scope in high yield. Zinc complex 1c exhibits a versatile substrate scope and good functional group tolerance for catalytic hydroboration reactions. A most plausible mechanism is proposed on the basis of the kinetic study

Highly Chemoselective Hydroboration of Alkynes and Nitriles Catalyzed by Group 4 Metal Amidophosphine–Borane Complexes

We report a series of titanium and zirconium complexes supported by dianionic amidophosphine–borane ligands, synthesized by amine elimination and salt metathesis reactions. The TiIV complex [{Ph2P(BH3)N}2C6H4Ti(NMe2)2] (1) was obtained by the reaction between tetrakis-(dimethylamido)titanium(IV) and the protic aminophosphine–borane ligand [{Ph2P(BH3)NH}2C6H4] (LH2) at ambient temperature. Both the heteroleptic zirconium complexes—[η5-(C5H5)2Zr{Ph2P(BH3)N}2C6H4] (2) and [[{Ph2P(BH3)N}2C6H4]ZrCl2] (3)—and the homoleptic zirconium complex [[{Ph2P(BH3)N}2C6H4]2Zr] (4) were obtained in good yield by the salt metathesis reaction of either zirconocene dichloride [η5-(C5H5)2ZrCl2] or zirconium tetrachloride with the dilithium salt of the ligand [{Ph2P(BH3)NLi}2C6H4] (LLi2), which was prepared in situ. The molecular structures of the complexes 1, 2, and 4 in their solid states were confirmed by single-crystal X-ray diffraction analysis. Of these complexes, only titanium complex 1 acts as an effective catalyst for the facile hydroboration of terminal alkynes, yielding exclusive E-isomers. The hydroboration of organic nitriles yielded diborylamines with a broad substrate scope, including broad functional group compatibility. The mechanism of hydroboration occurs through the formation of titanium hydride as an active species

Aluminium complex as an efficient catalyst for the chemo-selective reduction of amides to amines

We report an efficient protocol for the catalytic chemo-selective reduction of tert-amides with pinacolborane (HBpin) to afford the corresponding amines in high yields using aluminium complexes [κ2-{Ph2P(X)NC9H6N}Al(Me)2] [X = S (2a), Se (2b)] as pre-catalysts at room temperature. The aluminium complexes were prepared from the reaction of [Ph2P(X)NC9H6N] [X = S (1a), Se (1b)] and trimethylaluminium in toluene. The solid-state structure of complex 2b is established. Tertiary amides with a wide array of electron-withdrawing and electron-donating functional groups were easily converted to the desired products through the selective cleavage of the amides' CO bond by aluminium hydride as an active species. A kinetic study of the catalytic reaction is also reported

Aluminium complex–catalysed hydroboration of alkenes and alkynes

We demonstrate an efficient method for the hydroboration of terminal alkenes or alkynes with pinacolborane (HBpin) using the aluminium catalyst, [κ2-(Ph2P(=Se)NCH2(C5H4N)Al(CH3)2] (1), supported by a functionalized amidophosphine ligand under mild and solvent-free conditions to afford corresponding alkyl and alkenyl boronate esters in high yield. This protocol involves the chemoselective formation of an anti-Markovnikov product exclusively. Both terminal alkenes and alkynes bearing a wide array of electron-withdrawing as well as donating functional groups can easily be converted to the corresponding product through the formation of aluminum hydride as an active catalytic species

Alkali Metal Complex–Mediated Ring-opening Polymerization of rac-LA, ε-Caprolactone, and δ-Valerolactone

A series of alkali metal complexes formed by N-(2-fluoro/2-nitro phenyl)-P,P-diphenylphosphinoselenoic amide [(Ph2P(Se)NH(2-RC4H4)] [R = F (1-H); NO2 (2-H)] ligands with molecular formulas [M(THF)2(Ph2P(Se)N(2-RC4H4)] [M = Li, R = F (3a), NO2 (3b)] and [M(THF)2(Ph2P(Se)N(2-RC4H4)] [M = Na, R = F (4a), NO2 (4b); M = K, R = F (5a), NO2 (5b)] have been synthesized in great yield and fully characterized. The molecular structures of protic-ligands 1-H and 2-H, and alkali metal complexes 3b, 4a, and 4b were analyzed using single-crystal X-ray diffraction analysis. Sodium and potassium complexes 4a,b and 5a,b were proved to be active catalysts for the ring-opening polymerization (ROP) of rac-LA (rac-LA), ε-caprolactone, and δ-valerolactone at room temperature only. The best isoselectivity of poly(lactide) (PLA) was achieved to a high value of Pi = 0.78 using sodium complex 4b. One exceedingly dynamic potassium complex (5a,5b) even can catalyze the polymerization of 1,000 counterparts of rac-LA and yield polylactide with a high molecular weight and narrow polydispersity record (PDI). Experimental outcomes also showed steric hindrance, and electronic impacts have noteworthy consequences for this catalysis in the ROP of rac-LA

A highly efficient Ti-catalyst for the deoxygenative reduction of esters under ambient conditions: experimental and mechanistic insights from DFT studies

In this paper, we report the synthesis of dianionic amidophosphineborane-supported titanium chloride [{Ph2P(BH3)N}2C6H4TiCl2] (1) and TiIV alkyl complex [{Ph2P(BH3)N}2C6H4Ti(CH2SiMe3)2] (2) using a salt metathesis reaction. TiIV complex 1 was obtained by the reaction of the bis-borane ligand [{Ph2P(BH3)NH}2C6H4] and TiCl4 in toluene followed by the addition of 2 equivalents of [LiN(SiMe3)2] at ambient temperature. TiIV bis-alkyl complex 2 was isolated from the reaction of complex 1 with 2.5 equivalents of LiCH2SiMe3 in toluene. The solid-state structure of complex 1 is established by single-crystal X-ray diffraction analysis. TiIV bis-alkyl complex 2 has proved to be a competent catalyst in the deoxygenative reduction of aliphatic and aromatic esters with pinacolborane (HBpin) to afford corresponding boryl ethers at room temperature under solvent-free conditions. Catalyst 2 exhibits chemoselectivity toward ester functionalities over halides, heteroatoms, olefins, and amino functional groups. DFT studies demonstrate that the active form of catalyst 2 is capable of easily transferring its hydrides to ester substrates at room temperature. The studies further reveal that the rate-limiting step (RLS) in an ester-to-boryl ether conversion is the cleavage of the C-O bond of an ester. In brief, the titanium-catalysed ester-to-boryl ether conversions are found to be downhill processes having small activation barriers along all mechanistic steps. © 2022 The Royal Society of Chemistry