Tripropyltin(iv) complexes with some selected bioligands in 50% v/v dioxane/water mixture

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Biochemistry

Background:

• Organotin compounds exhibit diverse biological activities.
• Understanding the coordination behavior of organotins with biomolecules is crucial for assessing their environmental and toxicological impact.
• Tri-n-propyltin(IV) (TPT) is a relevant organotin species with potential biological interactions.

Purpose of the Study:

• To investigate the complexation of tri-n-propyltin(IV) (TPT) with selected bioligands.
• To determine the hydrolysis constants and stepwise formation constants of TPT complexes.
• To elucidate the role of functional groups in the binding of organotin to bioligands.

Main Methods:

• Potentiometric titration was employed to study the interactions.
• Experiments were conducted at 25°C and 0.1 M ionic strength in a 50% dioxane/water mixture.
• Complex formation constants were calculated using the nonlinear least-square program MINIQUAD-75.

Main Results:

• TPT undergoes hydrolysis, forming species such as [(C3H7)3SnOH], [(C3H7)3Sn(OH)2]-, and [((C3H7)3Sn)2OH]+.
• Amino acids and DNA constituents form both 1:1 and 1:2 complexes with TPT.
• Peptides form 1:1 complexes, involving deprotonated amide species and protonated complexes with amino acids, peptides, and some DNA constituents.

Conclusions:

• The study successfully quantified the complexation behavior of TPT with various bioligands.
• Functional groups on the ligands play a significant role in the binding affinity towards organotin.
• Speciation diagrams illustrate the pH-dependent distribution of different TPT complex species in solution.