A new dendrimer series: synthesis, free radical scavenging and protein binding studies

Abstract

Tri-o-tolyl benzene-1,3,5-tricarboxylate (TOBT (T0)), tri-4-hydroxyphenyl benzene-1,3,5-tricarboxylate (THBT (T1)), and tri-3,5-dihydroxyphenyl benzene-1,3,5-tricarboxylate (TDBT (T2)), a series of 1^st tier dendrimers with a common 1,3,5-benzenetricarbonyl trichloride/trimesoyl chloride (TMC) core, are reported. T0 does not have any replaceable H⁺ on its terminal phenyl group, acting as a branch. T1 has one phenolic –OH at the para position and T2 has two phenolic –OH groups at the 3 and 5 positions of each terminal phenyl group. During synthesis, these –OH groups at the terminal phenyl groups were protected through tert-butyldimethylsilyl chloride (TBDMSCl) assisted with t-BuOK in DCM, THF, indazole, 4-dimethylaminopyridine (DMAP), and tertiary-n-butyl ammonium fluoride (TBAF). MTBDMSP (mono-tertiary butyl dimethylsilane phloroglucinol), DTBDMSP (di-tertiary butyl dimethylsilane phloroglucinol), and TTBDMSP (tri-tertiary butyl dimethylsilane phloroglucinol) were obtained with >90% yield, and TTBDMSP phenolic derivatives (PDs) were developed to synthesize T0, T1, and T2 dendrimers by deprotecting with TBAF. T0 showed superhydrophobic properties as it did not dissolve in methanol, contrary to T1 and T2, but dissolved in acetone. Their structures were determined using ¹H and ¹³C NMR spectroscopies, and mass spectrometry. Their scavenging activities were studied using UV-Vis spectrophotometry compared with ascorbic acid and protein binding was studied with bovine serum albumin (BSA) and lysozyme (lyso). T0 exhibited exceptional optical activity contrary to T1 and T2, which acted as antioxidants to scavenge free radicals.