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The effect of halogen on arylsulfonylated phenothiazines for solid-sate
luminescence and photocatalytic performance
Caiyan Liu, a,‡ Yongli Shen, a,‡ Yunfeng Zhao,a Kaiqi Ye,b and Kedong Yuan a,*
a
Tianjin Key Laboratory of Advanced Functional Porous Materials, Institute for New Energy Materials & Low-Carbon Technologies, School
of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, PR China.
b
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, PR China.
‡ These authors contributed equally to this paper.
Abstract
Halogen atom effect on organic luminescence materials incorporating arylsulfonylated phenothiazine as
the central unit was investigated in both solid state and organic solution. New organic solids with very
weak C-halogen…π interactions are constructed, in which the packing style totally avoids the face-to-
face stacking. Consequently, a high solid luminescent efficiency (81.37%) is obtained from a fluorine-
substituted organic molecule crystal. The halogen atom effect on photocatalytic reaction was evaluated
using arylsulfonylated phenothiazines, which catalyzed dehydrogenative coupling of amines to imines
by simple blue light irradiation of the acetonitrile solution under aerobic atmosphere. The chlorine-
substituted photocatalyst exhibited a higher reactivity than other ones, providing a preliminary insight
for rational photocatalysts modification.
Keywords: Halogen atoms; C-X…π Interaction; Luminesence; Photocatalysis
1. Introduction
Organic luminescence materials have attracted significant attentions due to the growing demands in
[1]
[2]
the field of organic optoelectronic applications, such as organic light emitting devices (OLEDs),
laser amplifiers, [3] sensors, [4] and photocatalysis [5]. Recently, there has been increasing interest in the
study of the phenothiazine based organic photoreactive materials, for which functionalized
phenothiazines featuring the tunable donor-acceptor structures have played the key roles in the properties
of phenothiazine based organic semiconductor [6], dye sensitized solar cell [7] and photocatalysis [8]
.
Generally, large conjugated aromatic groups are the key to contribute to the luminescence property,
and the individual conjugated molecules are assembled together by noncovalent interactions. However,
strong interactions, such as π…π interactions and hydrogen bonding, can normally induce the
luminescence quenching in the solid state and the emission will shift to red wavelength synchronously.
[9,10] The quenching effect will cause molecules that have very high luminous efficiency in solution to
lose their original performance in the device, and the red-shift phenomenon will make the color purity
of the blue emission organic material deteriorated.[11] Constructing molecular assemblies through very
weak interactions has been proved as an effective strategy to obtain high efficiency solid illuminants. [12]
Therefore, it is of vital importance to obtain ideal luminescent solid materials by tuning the weak
[13]
interactions between molecules. Halogen-bonds (XB)
are very weak intermolecular noncovalent
interactions among various of weak interactions (e.g. hydrogen bonding, weak π-π interactions, C-H…π
interactions, metal-metal interactions), and a large group of XBs actually can work together in various