Unidirectional growth of organic single crystals of naphthalene, anthracene and pyrene by isothermal expansion of supercritical CO2.

Antaram Sarve,Jimil George,Santosh Agrawal,Raksh Vir Jasra,Pradip Munshi

doi:10.1039/d0ra03706k

Abstract

Unidirectional single crystals without grain boundaries are highly important in optoelectronic applications. Conventional methods to obtain such crystals involve organic solvents or seed crystals, which have numerous drawbacks. We present here a supercritical CO2-mediated method of the single crystal formation of naphthalene, anthracene and pyrene on the (001) plane without using seed crystals. Single dominant peaks in powder XRD (PXRD) with low full width at half maxima (FWHM) are described. The dependency of crystal size on the rate of depressurization was measured by precise and isothermal expansion of scCO2 solutions. The experimental setup is illustrated for continuous preparation without emission of CO2 or discharge of material into the environment. The materials are shown to be fully converted into crystals indicating a rapid, scalable and environmentally benign process of single crystal formation with practically nil E factor.

Highlights

Unknown to date, the masoning of molecules is demonstrated by growing organic crystals unidirectionally on the (001) plane through isothermal expansion of a supercritical CO2 solution (Fig. 1a)
We present here a supercritical CO2-mediated method of the single crystal formation of naphthalene, anthracene and pyrene on the (001) plane without using seed crystals
The masoning of molecules is demonstrated by growing organic crystals unidirectionally on the (001) plane through isothermal expansion of a supercritical CO2 solution (Fig. 1a)

Summary

Introduction

The masoning of molecules is demonstrated by growing organic crystals (naphthalene, anthracene and pyrene) unidirectionally on the (001) plane through isothermal expansion of a supercritical CO2 (scCO2) solution (Fig. 1a). SCFs have numerous applications in material processing and crystallization due to their unique properties, namely high diffusivity (diffusion coefficient 70 000 m2 sÀ1), high compressibility and higher solvency.[10] It was perhaps Hannay and Hogarth who rst observed particle formation from a supercritical solution in 1879.11 They described the phenomenon as ‘formation of snow’. This pioneering nding was unnoticed for about 100 years until Krukonis in 1985 took an interest and investigated the economic viability of supercritical uid-mediated processes.[12] Smith and coworkers later referred to the process as ‘rapid expansion of supercritical solutions’ (RESS).[13]

Results

Discussion

Conclusion