Following the footprints of aggregation in aniline and normal alkanols
Fan H. Holikulov U. Khudaykulov B. Yelemessova Z. Gilani A.G. Benassi E.
1 March 2026Elsevier B.V.
Journal of Molecular Liquids
2026#445
Polyaniline is one of the most promising conducting polymers, and its synthesis demands a detailed understanding of anilines (ANL) interactions with solvents. Herein, the intermolecular interactions formed between ANL and a series of n -alkanols (AlkOH) — viz. methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, and 1-octanol — were investigated using vibrational spectroscopy (FT-IR and Raman) and UV–Vis fluorescence spectroscopy, quantum mechanical calculations, and morphological characterisation. These systems exhibit considerable complexity due to the potential coexistence of ANL-ANL dimers in multiple configurations, both with and without alcohol participation. Spectroscopic analyses confirmed the formation of tri-molecular [ANL·(AlkOH)₂] clusters, with methanol (MeOH) displaying unique behaviour compared to longer-chain alkanols. In the [ANL·(MeOH)₂] cluster, one MeOH molecule adopts a perpendicular orientation of its OH group relative to the aniline phenyl ring, while the second MeOH forms a Me–O(H)⋯HNH–C₆H₅ hydrogen bond. For other alkanols, a different [ANL·(AlkOH)₂] configuration was identified, wherein aniline bonds simultaneously to two alcohol molecules via its amino hydrogen atoms. Although alternative clusters ( e.g. , [ANL₂·AlkOH] or [ANL₂·(AlkOH)₂] ) could theoretically exist, vibrational spectroscopy data did not provide sufficient evidence for their significant populations. Both [ANL·(AlkOH)₂] cluster types exhibited distinct molecular electrostatic potentials (positive and negative regions), likely promoting inter-cluster interactions and subsequent aggregation. SEM imaging revealed a predominant circular morphology (ranging from hundreds of nanometers to several micrometers) across all six systems. A secondary morphological feature was observed in all cases except the ANL-MeOH system. Moreover, the aggregation was characterised by the fluorescence of all six binary mixtures at x ANL = 0.1, corroborating the hypothesis of aggregation and heterogeneity/anisotropy of the binary systems. This study provides the first molecular-level model, revealing two distinct structural classes of trimolecular [ANL·(AlkOH)₂] clusters that explain the observed macroscopic aggregation and morphological features.
Aniline , Hydrogen bond , Linear alkyl alcohols , Molecular spectroscopies , Quantum chemical calculations
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Department of Chemistry, School of Sciences and Humanities, Nazarbayev University, Qabanbay Batyr 53, Astana, 010000, Kazakhstan
Department of Optics and Spectroscopy, Samarkand State University, University blvd. 15, Samarkand, 140104, Uzbekistan
Faculty of Natural Sciences, Department of Chemistry, L.N. Gumilyov Eurasian National University, Astana, 010000, Kazakhstan
Department of Applied Chemistry, Faculty of Chemistry, University of Guilan, Rasht, 4193833697, Iran
TIES Srl, Piazza Renato Simoni 1, Verona, 37122, Italy
Department of Chemistry
Department of Optics and Spectroscopy
Faculty of Natural Sciences
Department of Applied Chemistry
TIES Srl
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