Synthesis and antagonistic evaluation of fluorinated imidazolium salt [1-(2,6-diisopropylphenyl)-3-(2-fluoro-benzyl)-1H-imidazol-3-ium bromide] against significant phytopathogens in agriculture

The current investigation evaluated the in vitro bioefficacy of a newly synthesized unsymmetrical imidazolium
salt [1-(2,6-diisopropylphenyl)-3-(2-fluoro-benzyl)-1H-imidazol-3-ium bromide] that contains the electron-
withdrawing fluorine atom at the ortho position against agriculturally significant phytopathogens. The molec
ular structure of the imidazolium salt was characterized by various spectroscopic techniques such as 1H, 13C, and
19F NMR, FTIR, and high-resolution mass spectrometry (HRMS). Antimicrobial bioassay of the compound has
been tested against two Gram-negative, bacterial phytopathogens namely Ralstonia solanacearum (Rs) (Gen Bank
accession no. OQ743450) [causal agent: bacterial wilt of solanaceous crops], and Xanthomonas citri pv. citri (Xcc)
(Gen Bank accession no. OR7036310) [causal agent: citrus canker in citrus trees] and two fungal phytopathogens
namely Fusarium solani (Gen Bank accession no. OR140825) [causal agent: Fusarium die-back in tea] and
Pseudopestalotiopsis chinensis (Gen Bank accession no. OR140826) [causal agent: grey blight in tea]. Different
concentrations of imidazolium salt was tested against the target phytopathogens using the in vitro antimicrobial
bioassay through disc diffusion method. The imidazolium salt demonstrated a maximum percentage inhibition of
16.70 and 21.78 against the bacterial phytopathogens R. solanacearum, and X. citri pv. citri, respectively, at a
concentration of 2000 ppm over negative control. Similarly, the compound demonstrated promising antagonism
against the tea fungal pathogens F. solani and P. chinensis (percentage inhibition up to 61.43 and 80.84,
respectively at 2000 ppm) over negative control. Five replications were maintained in each of the cases. The
present investigation demonstrated the potential of fluorinated imidazolium salt as commercial antimicrobial
agent in integrated disease management schedule to control significant phytopathogenesis in agriculture
including in tea.