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

Abstract Hydrogen‐bonded organic framework‐based host–guest ultralong organic phosphorescence (HOF‐based HGUOP) materials with phosphorescent thermochromism property will become the next generation of intelligent optical functional materials in the future. Herein, three base‐tuning HOF‐based HGUOP co‐crystal materials, Ma&Ct, Ma&Ae and Ma&Tm, are firstly created by respectively doping 1 mol% cytosine (Ct), adenine (Ae) and thymine (Tm) into melamine (Ma) host, these guests respectively lead to the blue shift, red shift and quenching of phosphorescence for Ma host. Notably, Ma&Ct performs an intensive “1 + 1 > 2” sensitized effect for photoluminescence (PL) and phosphorescence based on various synergetic interactions, the PL and phosphorescence quantum yields respectively get to 94.55 and 37.11%. The concentration and temperature‐dependent photophysical performances of Ma&Ct, Ma&Ae and Ma&Tm are also recorded and analyzed. Relative mechanisms of phosphorescent thermochromism are firstly investigated deeply for Ma&Ct, Ma&Ae and Ma&Tm. In addition, phosphorescent thermochromism property of Ma&Ct and Ma&Ae have been well employed for information security and phosphorescent thermometer applications. This work not only proposes a simple preparation method of these new‐type base‐tuning HOF‐based HGUOP co‐crystal materials, but also explores the new internal phosphorescent thermochromism mechanism of these HOF‐based HGUOP materials, which provides a typical case of HOF‐based HGUOP materials using as smart flexible wearable phosphorescent thermometer.