Abstract
The structure of alpha-amino acids offers the possibility of the formation of a large number of forms coordination compounds with cations of metals All forms of amino acids can participate in complexation reactions with metal cations: protonated form with metal ions adducts by coordinating with unshared electron pairs of oxygen atoms of carboxyl groups, the stability constants of such complexes are small and they usually like solvate complexes; bipolar and deprotonated forms not only adducts, but also chelation. The study of equilibrium in the system of amino acid - metal cation are most often carried out potentiometric and spectrophotometric methods, allowing fast, with good reproducibility to determine the equilibrium concentration and composition of the solution without displacement of the chemical equilibrium. In the literature, a chelate compound of leucine with copper (II) cations, formed in an alkaline medium with stability constants of 7.89 and 6.45, has been studied in sufficient detail. This paper presents a study of the conditions of complex formation in neutral aqueous solutions in the system containing aliphatic amino acid L, D-leucine and copper cations (II). The difference in the wavelengths corresponding to the maximum optical density indicates a change in the composition of the aqueous solution and the presence of copper leucinate compounds. The existence of a complex compound between bipolar leucine ions and copper (II) cations in neutral aqueous solutions of the composition (СuLеu4)2+ was proved by the spectrophotometric method of isomolar series. For the determination of stability constants using the method of J. Bjerrum with the following assumptions: an amino acid was regarded as monobasic weak acid, the stability constant of complex compounds was calculated as the average of all functional groups of leucine. Defined in the work a measure of stability constants protonated compounds composition (СuLеu4)2+ is equal to 4.27.
Highlights
This paper presents a study of the conditions of complex formation in neutral aqueous solutions in the system containing aliphatic amino acid L, D-leucine and copper cations (II)
CONFLICT OF INTEREST The authors declare no conflict of interest
Summary
Изучение условий комплексообразования в нейтральных водных растворах проводили на примере системы, содержащей алифатическую аминокислоту L, D-лейцин и нитрат меди(II). Для определения состава соединения лейцина с медью использовали спектрофотометрический метод изомолярных соотношений, основанный на определении отношения концентраций реагирующих веществ, соответствующих образующемуся комплексному соединению. Спектры поглощения раствора лейцина и раствора лейцина с внесенным раствором Cu(NО3) получали относительно раствора сравнения – бидистиллированной воды. Для определения устойчивости соединения лейцина с медью использовали потенциометрический метод. Титровали исходный раствор лейцина и раствор комплексного соединения лейцина с медью установленного состава. Для этого в стакан вносили 25 см лейцина с концентрацией 0,1 моль/дм, из градуировочной бюретки последовательно вводили по 0,5 см раствора NаОН с концентрацией 0,05 моль/дм. Затем проводили в тех же условиях титрование лейцина раствором НСl с концентрацией 0,05 моль/дм. При рН-метрическом титровании комплексного соединения в стакан вносили 10 см раствора лейцина с концентрацией 0,1 моль/дм и 10 см раствора нитрата меди(II) с концентрацией 0,05 моль/дм
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the Voronezh State University of Engineering Technologies
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
