Azo compounds yog ib chav kawm ntawm cov organic molecules yam ntxwv los ntawm pawg azo (-N=N-). Lawv cov khoom tshwj xeeb photoisomerization ua rau lawv muaj txiaj ntsig hauv lub teeb -cov ntaub ntawv tswj hwm, bioimaging, thiab kev paub. Lub hauv paus ntsiab lus ntawm kev ua haujlwm tseem ceeb ntawm cov tebchaw no yog los ntawm kev thim rov qab cis- cov txheej txheem trans isomerization uas tau tsav los ntawm kev sib koom ua ke ntawm cov teebmeem hluav taws xob thiab steric hindrance ntawm cov hloov pauv ntawm ob qho kawg ntawm pawg azo.
Nyob rau hauv lub xeev av, azo tebchaw feem ntau muaj nyob rau hauv ib tug thermodynamically ruaj khov trans qauv: ob aromatic rings los yog alkyl chains yog linearly teem, thiab lub conjugated system txuas mus, ua rau cov molecule nqus cov wavelengths uas pom los yog ze ntawm - ultraviolet lub teeb. Thaum zoo siab los ntawm lub zog -matched photons, electrons dhia los ntawm kev sib txuas π orbitals mus rau cov antibonding π * orbitals, ua rau reconfiguration ntawm intramolecular nqi tis thiab tsis muaj zog lub π-bond yam ntxwv ntawm N=N ob daim ntawv cog lus. Nyob rau ntawm lub sijhawm no, ib qho -bond rotation barrier txo qis, thiab cov molecule tuaj yeem hloov mus rau hauv cov qauv cis los ntawm kev sib hloov nyob ib ncig ntawm N=N axis- ob lub nplhaib uas muaj ntxhiab tsim ib qho kev sib hloov khoov vim yog qhov tsis muaj zog, thiab qhov tsis muaj zog ntawm kev sib txuas ua rau muaj kev hloov pauv ntawm lub ntsej muag xiav. Cov txheej txheem photoisomerization no yog qhov thim rov qab heev: nyob rau hauv thermal so lossis irradiation nrog lwm lub wavelength ntawm lub teeb (xws li pom lub teeb), cov molecule tuaj yeem rov qab mus rau lub xeev trans, ua tiav "duab-hloov" voj voog.
Lub functionality ntawm azo tebchaw nyob ntawm cov kev hloov nyob rau hauv macroscopic zog tshwm sim los ntawm conformational hloov. Piv txwv li, qhov sib txawv ntawm qhov kev sib txawv ntawm cov qauv trans thiab qhov tsis yog -planarity ntawm cov qauv cis cuam tshuam rau cov qauv sib xyaw molecular, yog li hloov pauv qhov ntsuas qhov cuam tshuam, cov kua siv lead ua theem hloov pauv kub, lossis qhov ntub dej ntawm cov khoom. Yog hais tias lub molecule txuas mus rau lub pob txha polymer, nws cov conformational inversion tuaj yeem ua rau cov saw ntu txav, ua kom muaj zog tswj cov khoom siv kho tshuab. Hauv cov kab ke lom neeg, kev thim rov qab isomerization ntawm pawg azo tuaj yeem ua rau kev tso tawm ntawm cov tshuaj molecules lossis hloov pauv ntawm cov protein hloov pauv, muab cov txiaj ntsig rau cov tshuaj precision.
Nws yog ib qho tseem ceeb uas qhov cuam tshuam hluav taws xob ntawm cov khoom siv hloov pauv (xws li electron- pab pawg pab txhawb cov polarity ntawm N=N bonds) thiab steric hindrance (xws li pab pawg loj txwv kev ruaj ntseg ntawm cis conformation) cuam tshuam rau isomerization efficiency thiab photoresponse tus nqi. Los ntawm kev ua kom zoo dua cov kev ntsuas no los ntawm kev tsim qauv molecular, cov khoom siv hluav taws xob zoo nkauj ntawm azo tebchaw tuaj yeem hloov kho, nthuav lawv daim ntawv thov scenarios hauv cov ntse photoresponse systems. Nws cov ntsiab lus yog los hloov lub teeb lub zog rau hauv cov ntaub ntawv sib txawv ntawm cov molecular conformation los ntawm kev tswj cov kev hloov pauv ntawm kev ywj pheej nyob rau hauv molecules los ntawm lub teeb quantum tswj, thiab thaum kawg ua tiav cov lus teb ntse rau sab nraud stimuli.
