Hydrogen‐Bonded Organic Aromatic Frameworks for Ultralong Phosphorescence by Intralayer π–π Interactions

Abstract

Ultralong organic phosphorescence (UOP) based on metal-free porous materials is rarely reported owing to rapid nonradiative transition under ambient conditions. In this study, hydrogen-bonded organic aromatic frameworks (HOAFs) with different pore sizes were constructed through strong intralayer π-π interactions to enable ultralong phosphorescence in metal-free porous materials under ambient conditions for the first time. Impressively, yellow UOP with a lifetime of 79.8 ms observed for PhTCz-1 lasted for several seconds upon ceasing the excitation. For PhTCz-2 and PhTCz-3, on account of oxygen-dependent phosphorescence quenching, UOP could only be visualized in N , thus demonstrating the potential of phosphorescent porous materials for oxygen sensing. This result not only outlines a principle for the design of new HOFs with high thermal stability, but also expands the scope of metal-free luminescent materials with the property of UOP.

Organic Room Temperature Phosphorescence Materials for Biomedical Applications

“…Apart from the mentioned intermolecular interactions, the interlayer π‐π interaction can also be employed to trigger RTP. Based on this concept, our group initially reported hydrogen‐bonded organic aromatic frameworks (HOAFs) to obtain ultralong organic phosphorescence (molecule 21 ). In addition, we also synthesized a class of supramolecular frameworks by self‐assembly of melamine and aromatic acids in aqueous media and achieved ultralong organic phosphorescence with a long‐lived lifetime of up to 1.91 s and highly phosphorescence quantum efficiency of 24.3% simultaneously .…”

“…One is to facilitatie the intersystem crossing (ISC) from the lowest excited singlet state (S 1 ) to a triplet state (T n ) to populate the triplet excitons, and the other is to inhibit non‐radiative transitions from the lowest excited triplet state (T 1 ) to the ground state (S 0 ). On the basic of these factors, researchers have proposed various strategies and methods to moldulate phosphorescent performance, such as intruduction of heavy atoms, heteroatoms and aromatic carbony to boost SOC; while suppressing non‐radiation of the triplet excitons by host‐guest doping method crystalization and organic flameworks . Therefore, developing metal‐free organic luminescent materials with highly efficient room temperature phosphorescence has been becoming a hot topic in recent years …”

Carbon Dots with Dual‐Emissive, Robust, and Aggregation‐Induced Room‐Temperature Phosphorescence Characteristics

“…In the solid state, however, emission spectrum of the TA‐CDs actually contains both FL and RTP under direct irradiation, of which the emission at about 430 nm being FL and the emergence of emission peaks at about 465 and 550 nm arising from contributions of RTP. Furthermore, the activation of RTP from TA‐CDs powder could be attributed to their large conjugated structures that favoring to form aggregates owing to the strong π–π stacking . Such aggregation would not only play an important role for stabilizing the T 1 excited state of the TA‐CDs, but also form another triplet excited state (T 1 *) (Figure f) that probably being produced by delocalization among several neighboring T 1 emission relevant moieties …”

“…Furthermore,t he activation of RTP from TA-CDs powder could be attributed to their large conjugated structures that favoring to form aggregates owing to the strong p-p stacking. [63][64][65] Such aggregation would not only play an important role for stabilizing the T 1 excited state of the TA-CDs,b ut also form another triplet excited state (T 1 *) ( Figure 4f)t hat probably being produced by delocalization among several neighboring T 1 emission relevant moieties. [7,66] It is known that most of the currently reported organic RTPmaterials are only observable in crystalline or composite forms (that is,embedding in matrices), [6][7][8][9] which significantly limit their applications.F or instance,t he carbon precursor used in this study (namely,t rimellitic acid) shows such RTP properties (Supporting Information, Figure S19).…”

Controlled Growth of Ag Nanocrystals in a H‐Bonded Open Framework

“…Hydrogen-bonded open frameworks are an emergent class of microporous, molecule-based materials. [1][2][3][4][5][6] They are characterized by ar obust crystalline latticew ith large porosity resulting, like for MOF (metal-organic frameworks)a nd COF (covalento rganic frameworks), [7] in remarkable sorption properties [8][9][10][11][12] with possible applicationi ng as separation, [13][14] selective detection, [15] or drug encapsulation. [16] The majority of the reported H-bonded frameworksa re purely organic systemsk nown as HOF (H-bonded organic framework).…”