Preparation, Crystal Structure, and Solid-state Fluorescence of a CH2Cl2-solvated Crystal of 6,13-Bis(t-butylphenyl)-2,3,9,10-tetrapropoxypentacene

Abstract

Slow evaporation of 6,13-bis(t-butylphenyl)-2,3,9,10-tetrapropoxypentacene in CH2Cl2 solution in the dark, yielded CH2Cl2-solvated single crystals easily. The crystals were characterized by X-ray analysis and solid-state fluorescence.

Tuning the Solid‐State Optical Properties of Tetracene Derivatives by Modification of the Alkyl Side‐Chains: Crystallochromy and the Highest Fluorescence Quantum Yield in Acenes Larger than Anthracene

“…[4] In recent years, we have prepared various alkyl‐substituted tetracenes and we found that, as expected, the introduction of alkyl side‐chains into the tetracene framework facilitated their solubility in common organic solvents (even pure n ‐hexane), as well as providing relatively low melting points (about 100 °C). [5] During the course of this work, we observed a most‐interesting and unexpected result: the color of these materials in the solid state differed for compounds with different alkyl side‐chains. Specifically, in the solid‐state, the materials ranged in color from yellow to red, whereas in solution, they were all orange.…”

“…In particular, in the series of 1,4,7,10‐tetraalkyl‐ ( 1 – 6 ) and 1,4,7,10‐tetraisoalkyltetracenes ( 7 – 9 ), a small change in the substituent could cause considerable changes in the solid‐state color. For example, in the tetraalkyl series,[5b] the methyl‐, propyl‐, and pentyl derivatives ( 1 , 3 , and 5 ) were orange, the ethyl derivative ( 2 ) was yellow, the hexyl derivative ( 6 ) was red, and the butyl derivative ( 4 ) was a mixture of yellow and red, both of which could be separated. [5a] In this sequence, the number of carbon atoms in the alkyl substituent correlated with color as follows: compounds 2 and 4 were yellow solids, compounds 1 , 3 , and 5 were orange solids, and compounds 4 and 6 were red solids.…”

“…For example, in the tetraalkyl series,[5b] the methyl‐, propyl‐, and pentyl derivatives ( 1 , 3 , and 5 ) were orange, the ethyl derivative ( 2 ) was yellow, the hexyl derivative ( 6 ) was red, and the butyl derivative ( 4 ) was a mixture of yellow and red, both of which could be separated. [5a] In this sequence, the number of carbon atoms in the alkyl substituent correlated with color as follows: compounds 2 and 4 were yellow solids, compounds 1 , 3 , and 5 were orange solids, and compounds 4 and 6 were red solids. This trend was reminiscent of the structural regularity of various alkyl chain‐lengths and resembled the odd–even effect that has frequently been observed in liquid crystals.…”

“…[13] In contrast, in the tetraisoalkyl series ( 7 – 9 ), their colors had little correlation to those of their corresponding linear alkyl derivatives. [5d] For example, the isopropyl derivative ( 7 ) was yellow but the propyl derivative ( 3 ) was orange, the isobutyl derivative ( 8 ) was red but the butyl derivatives ( 4 ) were yellow and red, and the isopentyl derivative ( 9 ) was orange–yellow but the pentyl derivative ( 5 ) was orange. In contrast to the 1,4,7,10‐tetrasubstituted tetracenes, both the 2,3‐dialkyl‐ ( 10 – 13 ) and 2,3,8,9‐tetraalkyltetracenes ( 14 – 17 ) exhibited slight changes in the solid‐state color with alkyl chain‐length.…”

“…In contrast to the 1,4,7,10‐tetrasubstituted tetracenes, both the 2,3‐dialkyl‐ ( 10 – 13 ) and 2,3,8,9‐tetraalkyltetracenes ( 14 – 17 ) exhibited slight changes in the solid‐state color with alkyl chain‐length. [5e] For example, the 2,3‐dialkyl derivatives ( 10 – 13 ) were mostly orange whilst the 2,3,8,9‐tetraalkyl derivatives ( 14 – 17 ) were almost all yellow. Both the 2,3‐dialkyl‐ and 2,3,8,9‐tetraalkyl derivatives caused color changes in their propyl derivatives ( 10 and 14 , respectively).…”