Synthesis and Structure‐Photophysics Evaluation of 2‐N‐Amino‐quinazolines: Small Molecule Fluorophores for Solution and Solid State

Abstract

2‐N‐aminoquinazolines were prepared by consecutive SNAr functionalization. X‐ray structures display the nitrogen lone pair of the 2‐N‐morpholino group in conjugation with the electron deficient quinazoline core and thus representing electronic push‐pull systems. 2‐N‐aminoquinazolines show a positive solvatochromism and are fluorescent in solution and in solid state with quantum yields up to 0.73. Increase in electron donor strength of the 2‐amino substituent causes a red‐shift of the intramolecular charge transfer (ICT) band (300–400 nm); whereas the photoluminescence emission maxima (350–450 nm) is also red‐shifted significantly along with an enhancement in photoluminescence efficiency. HOMO‐LUMO energies were estimated by a combination of electrochemical and photophysical methods and correlate well to those obtained by computational methods. ICT properties are theoretically attributed to an excitation to Rydberg‐MO in SAC‐CI method, which can be interpreted as n‐π* excitation. 7‐Amino‐2‐N‐morpholino‐4‐methoxyquinazoline responds to acidic conditions with significant increases in photoluminescence intensity revealing a new turn‐on/off fluorescence probe.

Push-Pull Structures Based on 2-Aryl/thienyl Substituted Quinazolin-4(3H)-ones and 4-Cyanoquinazolines

“…Over the last two decades, there has been a remarkable increase in the number of fluorescent diaza-heterocycles [ 1 , 2 , 3 , 4 ]. Among them quinoxaline and quinazoline derivatives are considered as pH sensors [ 5 , 6 , 7 ], luminescent detectors [ 8 , 9 , 10 ], imaging agents [ 11 ], components for organic light-emitting diodes (OLED) materials [ 12 , 13 ], solar cells and organic photovoltaic [ 14 , 15 ], and so on. The fundamental work has been done for the establishment of detailed structure–property relationships (SPRs) providing beneficial information for fine-tuning of the key properties and the rational design and synthesis of fluorophores.…”

Synthesis and Antitrypanosomal and Mechanistic Studies of a Series of 2-Arylquinazolin-4-hydrazines: A Hydrazine Moiety as a Selective, Safe, and Specific Pharmacophore to Design Antitrypanosomal Agents Targeting NO Release

“…To support this evidence, we performed a fluorescence study for the resulting solution, and it was compared with that solution in the absence of an oxidant. It is documented that 2-aminoquinazolines present fluorescence properties with a normal emission at 400–430 nm and a secondary anomalous at 575–600 nm. − It is well known that the fluorometry is a high-sensitivity technique, which facilitated the detection of low-concentration compounds. From the fluorescence experiment, in general, all 2-arylquinazolin-4-hydrazines showed a maximum normal emission wavelength at 400 nm (Figures B–D and S8 and S9).…”

Design, Synthesis, and Photophysical Properties of 5-Aminobiphenyl Substituted [1,2,4]Triazolo[4,3-c]- and [1,2,4]Triazolo[1,5-c]quinazolines

“…Each of the fragments is of great interest owing to their electron withdrawing properties and use in the design of donor-acceptor small molecules displaying characteristics preferable for optical materials. The quinazoline component has been explored in the context of fundamental research [3][4][5], with some quinazoline derivatives revealed to have potential application in optoelectronics [6][7][8][9], detection of analytes [10,11], bioimaging [12], etc. [1,2,4]Triazole derivatives, in turn, are considered as blue phosphorescent, TADF emitters or host materials for OLED devices [13][14][15].…”