Research on Benzoyl Derivatives: Expanding Conjugated Structures to Enhance Free Radical Clearance and Antibacterial Properties

Research Overview: A study published in Polymers for Advanced Technologies synthesized two structurally different derivatives of benzoyl chloride through nucleophilic acyl substitution reaction starting from benzoyl chloride. Reacting with hydrazine hydrate to obtain phthalic anhydride dihydrazide (PA-1) with a yield of 80%; Reaction with benzidine yields N1, N4 bis (4 ′ – amino – [1,1 ′ – biphenyl] -4-yl) p-phenylenediamide (PA-2) with a yield of 77%. The product was characterized by FT-IR, NMR, SEM, PXRD, UV Vis, and TGA, and its antioxidant, antibacterial, and anti biofilm activities were evaluated. Molecular docking, molecular dynamics simulations, and density functional theory calculations were used to explain the results.

Performance Data

At a concentration of 50 μ g/mL, the DPPH radical scavenging rate of PA-2 is 82.49% ± 1.35%, and the ABTS radical scavenging rate is 82.80% ± 1.50%;

; In contrast, the corresponding values of PA-1 are 59.49% ± 1.54% and 58.44% ± 0.59%. In terms of antibacterial activity, PA-2 showed MIC values of 10-20 μ g/mL against the tested strains and exhibited biofilm inhibition rates of 51.89% -57.61%, all of which were superior to PA-1. The calculation results show that the HOMO-LUMO energy gap of PA-2 is 2.437 eV, which is smaller than the 3.271 eV of PA-1. Molecular docking and molecular dynamics simulations also predict that PA-2 has more favorable and stable interactions. The study attributed these results to the extended π – conjugated structure derived from benzidine in PA-2, which is believed to be associated with enhanced electronic responsiveness and multifunctional biological activity.

Significance for the polymer additive industry

From the perspective of electronic and electrical materials, the value of this work lies not in directly providing a commercially viable additive product, but in providing a class of structural design ideas that can be referenced.

. The high free radical scavenging ability exhibited by PA-2 shares similarities with the functional goal of antioxidants in inhibiting thermal oxidative aging in polymer matrices; The smaller energy gap brought by its extended conjugated structure also provides a computational basis for understanding the electronic responsiveness at the molecular level. For the application of engineering plastics in electronic and electrical scenarios, both weather stability and flame retardancy are usually performance dimensions that need to be considered simultaneously, with antioxidant components often involved. This study suggests that introducing biphenyl amine conjugated fragments into the benzoyl skeleton may improve the efficiency of free radical capture while altering the electronic structure of the molecule. This provides a reference for exploring multifunctional auxiliary molecules in polymer materials for electronic and electrical applications in the future. It should be pointed out that the activity evaluation of this study was conducted under solution or in vitro conditions, and did not involve processing stability, migration, compatibility, or interaction with flame retardant systems in the polymer matrix. Therefore, there is still a gap between the research results and the practical application in the formulation of engineering plastics. However, as a class of candidate molecules with clear structures, sufficient characterization, and accompanying computational explanations, PA-1 and PA-2 provide a verifiable starting point for molecular screening of antioxidants and multifunctional additives, and their subsequent performance in the evaluation of weather stability is particularly noteworthy.

Information source:Synthesis and Bioevaluation of Terephthalic Dihydrazide and a Benzidine‐Based Terephthalamide: Antioxidant, Antimicrobial, and Antibiofilm Activities With Computational Insights， Organized by Herun Chemical.