Fluorescent organic nanofibrils as sensory materials for explosives detection

Abstract

A class of fluorescent, organic nanofibrils, and particularly the films comprising entangled piling of these nanofibrils exhibiting effective quenching of their fluorescence upon exposure the vapor of explosives is disclosed. A sensor and a method for sensing the explosives vapor and other volatile organic compounds is disclosed, including the explosives taggants through the modulation of the fluorescence of the nanofibril film and the electrical conductivity of the nanofibrils. A development of synthetic methods is disclosed, such as protocols and techniques that lead to the production of various arylene-ethynylene macrocycle (AEM) molecules, which consist of a shape-persistent, toroidal scaffold in planar conformation, with minimal ring strain and highly tunable ring sizes (from 0.5 nm to above 10 nm). An approach to optimization of the one-dimensional molecular arrangement along the long axis of the nanofibril is also disclosed, which provides increased exciton migration and charge transport (via pi-electronic delocalization).

1 . A sensory film that consists of entangled piling of nanofibrils and demonstrates sensing efficiency independent on the film thickness. 
     
     
         2 . The sensory film as in  claim 1 , wherein the film consists of entangled piling of the nanofibrils, in thickness of 10 nm to 200 nm. 
     
     
         3 . The sensory film as in  claim 1 , wherein the sensing efficiency is defined as the percentage of quenching of the fluorescence of the nanofibril film. 
     
     
         4 . The sensory film as in  claim 3 , wherein the film-thickness-independence of the fluorescence quenching enables fabrication of a sensing film in a thickness that provides the best sensing efficiency and stability against photobleaching or photooxidation. 
     
     
         5 . The sensory film as in  claim 1 , wherein the film demonstrates fast time response to exposure to explosives vapor. 
     
     
         6 . The sensory film as in  claim 5 , wherein the time response is defined as the time needed to reach the saturation of the fluorescence quenching of the film after exposure to the explosives vapor, and for the films tested in the present invention the time response is about 10 seconds for exposure to TNT vapor at 5 ppb, or DNT vapor at 100 ppb. 
     
     
         7 . The sensory film as in  claim 2 , wherein the quenching time response is faster than the other organic based sensory films, including those fabricated from polymers and other organic molecules. 
     
     
         8 . The sensory film as in  claim 1 , wherein the sensory film demonstrates strong stability with regard to being repeatedly used in the explosives sensing via fluorescence quenching. 
     
     
         9 . The sensory film as in  claim 8 , wherein the repeated use of the film in fluorescence quenching is performed by recovering the fluorescence of the film (after being used in fluorescence quenching) back to the level of the pristine film before being used in fluorescence quenching. 
     
     
         10 . The sensory film as in  claim 9 , wherein the recovery of fluorescence of the film is processed by placing the film in open air for extended time or placing the film in a saturated vapor of hydrazine for hours. 
     
     
         11 . The sensory film as in  claim 1 , wherein the sensory film demonstrates strong stability against photobleaching or any other photo-damage. 
     
     
         12 . The sensory film as in  claim 11  wherein the stability test is performed by exposing the film to light irradiation for different amount of times. 
     
     
         13 . The sensory film as in  claim 1 , wherein the sensory film demonstrates efficient fluorescence quenching upon exposed to the vapor of explosives, including TNT and DNT. 
     
     
         14 . The sensory film as in  claim 1 , wherein the sensory film demonstrates efficient fluorescence quenching upon exposed to the vapor of explosives taggants, which are required additives in all legally manufactured explosives and plastic explosives devices. 
     
     
         15 . The sensory film as in  claim 14 , wherein a typical example of the explosives taggants is 2,3-dimethyl-2,3-dinitrobutane (DMNB). 
     
     
         16 . The sensor as in  claim 1 , wherein the entangled piling of nanofibrils operates at ambient conditions, the entangled piling of nanofibrils being robust against air, moisture, and room light or sun light irradiation.