Ag+-Induced Aromatic Complexation as a Tool for Complex Mixture Mesophase-Forming Performance Screening.

Mesophase pitch is a pivotal precursor for advanced carbon materials, yet feedstock selection still relies on time-consuming thermal polycondensation and ex situ microscopy. Here we report an Ag+-induced electrospray ionization high-resolution mass spectrometry (ESI-HRMS) strategy for rapid screening of mesophase-forming feedstocks in complex hydrocarbon systems. The method exploits the structural sensitivity of Ag+-induced aromatic complexation, quantified through the response of [2M + Ag]+ multicomplex ions. Model compound studies confirmed that Ag+ preferentially complexes with high-aromaticity, short-side-chain molecules, mirroring ideal mesophase precursor features. Across FCC slurry oils, residual oil, and supercritical fluid extraction fractions, the [2M + Ag]+ signal correlates positively with mesophase content and with the development of ordered mesophase texture. Collision-induced dissociation (CID) analysis further indicates that the dominant multicomplexes adopt an "aromatic-Ag+-aromatic" sandwich-like structure and are primarily contributed by short-side-chain 3-5-ring aromatics.