title: Temperature dependence of aggregated structure of β-carotene by absorption spectral experiment and simulation.
abstract: β-carotene can self-assemble to form J- or H-type aggregate in hydrophilic environments, which is crucial for the proper functioning of biological system. Although several ways controlling the formation of the two types of aggregate in hydrated ethanol have been investigated in recent years, our study provided another way to control whether J- or H- β-carotene was formed and presented a method to investigate the aggregated structure. For this purpose, the aggregates of β-carotene formed at different temperatures were studied by UV-Vis spectra and a computational method based on Frenkel exciton was applied to simulate the absorption spectra to obtain the aggregated structure of the β-carotene. The analysis showed that β-carotene formed weakly coupled H-aggregate at 15°C in 1:1 ethanol-water solvent, and with the increase of temperature it tended to form J-type of aggregate. The absorption spectral simulation based on one-dimensional Frenkel exciton model revealed that good fit with the experiment was obtained with distance between neighbor molecules r=0.82nm, disorder of the system D=1500cm(-1) for H-type and r=1.04nm, D=1800cm(-1) for J-type.
authors.affiliation: College of Science, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Lu
authors.affiliation: The High Pressure Research Center of Science and Technology, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.affiliation: College of Science, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Liangshu
authors.initials: L
authors.lastname: Wei
authors.affiliation: College of Science, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
mesh_terms: D003198:Computer Simulation; D019281:Dimerization; D000431:Ethanol / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D008958:Models, Molecular; D013053:Spectrophotometry; D013696:Temperature; D014867:Water / Q000737:chemistry; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D019207:beta Carotene; D014867:Water; D000431:Ethanol
keywords: Absorption spectra; Aqueous ethanol solution; Diagonal disorder; H- or J-aggregate; Index heading: Frenkel exciton