Triphenylamine-based fluorophores bearing peripheral diazine regioisomers. Synthesis, characterization, photophysics and two-photon absorption

A series of six tripodal push-pull fluorophores with D-(pi-A3) arrangement has been designed and synthesized. The structure of these fluorophores consists of a central electron-donating triphenylamine core and peripheral electron-withdrawing diazine units (pyridazine, pyrimidine, and pyrazine moieties), which are linked by an ethynylene pi-spacer. The preparation of the fluorophores involves threefold Sonogashira cross-coupling reaction starting from the key tris(4-ethynylphenyl)amine intermediate. The structure and spatial arrangement of two fluorophores were completely confirmed by X-ray analysis. Thermal and electrochemical behavior of prepared fluorophores were investigated by differential scanning calorimetry and cyclic voltammetry. Their linear optical properties were examined by UV-Vis absorption, steady-state and time resolved fluorescent spectroscopy while 2 PA analysis was used for a study of the nonlinear optical response. Experimental data were supported by DFT calculations. Based on the experimental as well as theoretical data, structure-property relationships have been thoroughly revealed.
Byla připravena série šesti tripodálních fluoroforů s D-(pi-A3) uspořádáním. Struktura derivátů obsahuje centrální elektronově donorní trifenylaminový skelet a postranní elektronakceptorní diaziny (pyridazin, pyrimidin, pyrazin) vázané přes ethynylenové můstky. Příprava je založena na trojnásobném Sonogashirově cross-couplingu z výchozího tris(4-ethynylfenyl)aminu. Struktura látek byla potvrzena rentgenostrukturní analýzou. Termální a elektrochemické vlastnosti byly zkoumány s pomocí DSC a cyklické voltametrie. Dále byla použita UV-Vis absorpční spektroskopie a 2 PA analýza. Experimentální výśledky byly konfrontovány s výsledky DFT kalkulací.