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The impact of hydrogen bond formation on the supramolecular assembly of two perylene imide derivatives (PMAMI and PDINH) was systematically investigated in solution and at the liquid-solid interface. PDINH has intrinsic hydrogen bond sites, but this is not the case for PMAMI. The solution assembly was explored by morphological methods (SEM, AFM, TEM and cryo-TEM) and spectral characterization (UV-vis, FL, XRD, and FTIR spectra). The surface assembly at the liquid-solid interface was detected by scanning tunneling microscopy (STM). It was found that in a mixed solution (THF/MeOH, 10 v%/90 v%), PMAMI formed nanofibers together with large sheet structures and PDINH assembled into uniform nanosheets, suggesting different molecular packing routes. The assembled structures could be adjusted by varying the solvent polarity for both molecules. At the liquid-solid interface, clearly distinguished surface nanostructures from PMAMI and PDINH were easily observed. Based on all spectral and morphological characterizations, it was suggested that in solution the assembly of PMAMI was mainly derived by π-π stacking interactions; on the other hand, the synergetic interaction of hydrogen bonds and π-π stacking was the reason for the hierarchical assembly of PDINH. Hydrogen bonds could be formed both for PMAMI and PDINH and stabilized nanostructures at the liquid-solid interface. This investigation could be useful in designing perylene imide-based building blocks for fabricating supramolecular assemblies with predetermined nanostructures and properties.

As in other countries, short-term rentals for tourism services are growing rapidly in China’s tourist cities, which are mainly operated through Airbnb. This paper explores whether the spatial distribution of Airbnb in China’s rapid urbanization process exhibits characteristics, paths, and drivers that are different from those of cities in other countries. Airbnb is a model for the global sharing economy, but it is increasingly influenced by other functions and facilities in cities as it grows. In this paper, the zero-expansion negative binomial regression was used to study the factors affecting the spatial distribution of Airbnb in Nanjing, China. The results showed that the spatial distribution of Airbnb listings was correlated with the distribution of cultural attractions, universities, public transport accessibility, shopping centers, and business apartments. By analyzing the driving forces of Airbnb’s development in Nanjing, this paper found that a large number of business apartments developed in cities were essential providers of Airbnb listings, and affected its spatial distribution. The gap between short-term and long-term rentals was also correlated with the distribution of Airbnb. In addition, similar to the previous literature findings, the increase in the proportion of professional hosts changes the original intention of Airbnb for sharing and communication. Our empirical results applies to the current situation of Airbnb in Chinese cities, which is conducive to the government’s more intelligent management and effective promotion of the Airbnb market. Our findings also provide positive references for urban renewal policies and public participation methods in China.

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