Halogen Bonding: A New Platform for Achieving Multi‐Stimuli‐Responsive Persistent Phosphorescence

Abstract

Monotonous luminescence has always been a major factor limiting the application of organic room‐temperature phosphorescence (RTP) materials. Enhancing and regulating the intermolecular interactions between the host and guest is an effective strategy to achieve excellent phosphorescence performance. In this study, intermolecular halogen bonding (CN⋅⋅⋅Br) was introduced into the host–guest RTP system. The interaction promoted intersystem crossing and stabilized the triplet excitons, thus helping to achieve strong phosphorescence emission. In addition, the weak intermolecular interaction of halogen bonding is sensitive to external stimuli such as heat, mechanical force, and X‐rays. Therefore, the triplet excitons were easily quenched and colorimetric multi‐stimuli responsive behaviors were realized, which greatly enriched the luminescence functionality of the RTP materials. This method provides a new platform for the future design of responsive RTP materials based on weak intermolecular interactions between the host and guest molecules.

Modulation of the intramolecular hydrogen bonding and push–pull electron effects toward realizing highly efficient organic room temperature phosphorescence

“…In the last decade, ultralong organic room temperature phosphorescence (UORTP) materials with durations ranging from several seconds to hours have become the focus of scientific research for their potential applications in optoelectronic technologies, [1][2][3][4][5][6] such as anti-counterfeiting, [7][8][9][10][11][12][13] information storage, [14][15][16][17][18] chem/biosensors, [19][20][21] and bioimaging. [22][23][24][25][26][27][28] Being superior in terms of structural versatility, flexibility, processability and biocompatibility, UORTP materials have displayed broader development prospects and are ideal alternatives to inorganic phosphors.…”

Base‐Tuning HOF‐Based Host–Guest Ultralong Organic Phosphorescence Systems with Phosphorescent Thermochromism Using for Information Security and Thermometer

“…Through TDDFT calculation, it can be found that S 1 (4.472 eV) state of Ct monomer is slightly lower than that (4.480 eV) of Ma/Ct dimer, and T 1 (3.234 eV) state of Ct monomer is lower than that (3.316 eV) of Ma/Ct dimer (Figure 3b,c), which illustrates that phosphorescence of Ma/Ct dimer will perform a blue shift compared with that of Ct monomer, and the sky‐blue phosphorescence is ascribed to Ma/Ct dimer. Through comparing the decay times of cyan (Ct monomer) with sky blue (Ma/Ct dimer) phosphorescence at 298 K, the decay time of sky‐blue phosphorescence is longer than that of cyan (Figure 3a), indicating that large amount of energy transferring from Ma host to Ma/Ct dimer, and little energy shifts to Ct monomer at 298 K. There is only a sky‐blue phosphorescence at 77 K for Ma&Ct (Figure S21, Supporting Information), with the growing temperature, thermal motion in Ma&Ct system becomes violent and intermolecular hydrogen bond of Ma/Ct dimer is broken to generate Ct monomer, [ 13 ] then the most energy transfers from Ma host to Ct monomer rather than Ma/Ct dimer at 393 K, the phosphorescent color changes to green at 393 K (Figure 3a), and the actual phosphorescence lifetime is continuously reduced from about 4.0 to 2.5 s (Figure 3a). The phosphorescent thermochromism progresses of Ma&Ct is reversible by cooling to 298 K, which can repeat for seven times (Figure 3d).…”

Manipulating room-temperature phosphorescencevialone-pair electrons and empty-orbital arrangements and hydrogen bond adjustment

“…By enhancing the temperature, molecular vibrations in the aggregated states were intensified and it was difficult to stabilize the excited triplet excitons. 44,45 Therefore, the proportion of the phosphorescent component of the steadystate spectrum decreased, and the color of photoluminescence correspondingly changed with temperature switching. When the temperature cooled down to room temperature, its steadystate emission returned to the initial state.…”