The use of indium tin oxide(ITO)and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine(a model amino acid)is reported.Commercially available ITO dots(<5 mm)attached to blank poly(me...The use of indium tin oxide(ITO)and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine(a model amino acid)is reported.Commercially available ITO dots(<5 mm)attached to blank poly(methyl)methacrylate(PMMA,5 cm in diameter with 21-well silicon isolators:referred to as the iCrystal plates)were found to withstand prolonged microwave heating during crystallization experiments.Crystallization of L-alanine was performed at room temperature(a control experiment),with the use of two microwave sources:a 2.45 GHz conventional microwave(900 W,power level 1,a control experiment)and 8 GHz(20 W)solid state,monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity.Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47±2.9 min,12±7.6 min and 1.5±0.5 min at room temperature,using a conventional microwave and focused monomode microwave heating,respectively.Complete evaporation of the solvent using the focused microwaves was achieved in 3.2±0.5 min,which is~52-fold and~172-fold faster than that observed at room temperature and using conventional microwave heating,respectively.The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method:33 crystals of 585±137μm in size at room temperature>37 crystals of 542±100μm in size with conventional microwave heating>331 crystals of 311±190μm in size with focused monomode microwave.FTIR,optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces.In addition,theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.展开更多
文摘The use of indium tin oxide(ITO)and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine(a model amino acid)is reported.Commercially available ITO dots(<5 mm)attached to blank poly(methyl)methacrylate(PMMA,5 cm in diameter with 21-well silicon isolators:referred to as the iCrystal plates)were found to withstand prolonged microwave heating during crystallization experiments.Crystallization of L-alanine was performed at room temperature(a control experiment),with the use of two microwave sources:a 2.45 GHz conventional microwave(900 W,power level 1,a control experiment)and 8 GHz(20 W)solid state,monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity.Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47±2.9 min,12±7.6 min and 1.5±0.5 min at room temperature,using a conventional microwave and focused monomode microwave heating,respectively.Complete evaporation of the solvent using the focused microwaves was achieved in 3.2±0.5 min,which is~52-fold and~172-fold faster than that observed at room temperature and using conventional microwave heating,respectively.The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method:33 crystals of 585±137μm in size at room temperature>37 crystals of 542±100μm in size with conventional microwave heating>331 crystals of 311±190μm in size with focused monomode microwave.FTIR,optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces.In addition,theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.
