Squaraic acid(3, 4. Dihydroxy 3-cyclobutene-1,2-dione, 1) yog ib qho ntawm cov neeg sawv cev ntawm cov khoom siv hauv cov pa oxygen (Oxocarbons), uas yog muab los ntawm nws cov qauv quaternary nplhaib thiab muaj zog acidity Lub npe yog thawj zaug synthesized los ntawm Cohen et alin 1959. Vim yog cov qauv tshuaj tshwj xeeb thiab cov khoom siv tshuaj lom neeg ntawm squaric acid, chemists los ntawm ntau lub teb chaws tau ua qhov kev tshawb fawb tob thiab dav ntawm chemistry ntawm squaric acid.
Squaric acid yog ib qho muaj zog dibasic acid, pK=0.5, pK 2-3.5. Vim muaj zog hydrogen bond ntawm molecules, nws melting point yog siab heev (> 300" C), thiab nws solubility nyob rau hauv dej txias tsuas yog 2. Sprenger npaj siab hais tias squaric acid molecules muaj ib tug resonance qauv. ntawm l-, lb, thiab lc, uas piav qhia txog cov qauv resonance Cov kev ruaj ntseg zoo thiab muaj zog electrophilic reactivity ntawm cov squaric acid molecule tau txhim kho.
Lub infrared spectrum ntawm squaric acid dianion (I) qhia tau hais tias tsis muaj carbonyl yam ntxwv ncov nyob rau hauv lub molecule, LC. AO' qhov kev suav ntawm lub zog thiab lub zog ntawm lub nroog ua pov thawj tias cov molecule yog cov qauv sib luag. Raws li Huckel' txoj cai, squaric acid divalent anion yog aromatic, thiab West koom nrog rau hauv cov pa roj carbon-oxygen aromatic system nrog cov tshuaj formula CO: ib. Lwm cov pa roj carbon thiab cov pa oxygen kuj suav nrog dihydroxy cycloacetone divalent anion (I), rosinate divalent anion (II) thiab crotonic acid divalent ion (IV).
Raws li ib tug raug molecule nyob rau hauv lub aromatic system ntawm carbon oxides, squaraine yog heev active nyob rau hauv tshuaj muaj pes tsawg leeg thiab muaj peev xwm hnov mob nrog ntau lub tebchaw thiab hu ua ib tug universal intermediate. Nws cov cocoon derivatives yooj yim xws li squaraine ester, squaraic acid amide thiab squaraic acid chloride kuj qhia txog kev ua haujlwm zoo. Kuv yog tsim los ntawm condensation ntawm squaraine thiab hluav taws xob nplua nuj rings xws li aromatic amines, phenols, thiab ammonia-muaj heterocyclic compounds. Squaraine cyanine compounds yog ib hom tshiab ntawm ze-infrared dyes nrog cov khoom zoo heev. Vim lawv cov khoom siv kho qhov muag zoo heev thiab lub teeb pom kev zoo thiab thermal stability, lawv cov kev tshawb fawb tau dhau los ua ib qho ntawm cov hotspots hauv kev tshawb fawb ntawm cov xim dyes nyob rau hauv xyoo tas los. Lub optical disc ua los ntawm cyanine squaraine dye txheej zaj duab xis tau siv nyob rau hauv cov ntaub ntawv siv, thiab nws tau pom zoo daim ntawv thov kev ua tau zoo nyob rau hauv lub teb ntawm kua siv lead ua zaub, organic solar roj teeb kev tshawb fawb, non-linear optical cov ntaub ntawv, LB tshawb fawb thiab hais txog. Tsis tas li ntawd, vim tias ntau cov xim squaraine muaj zog fluorescence emission nyob rau hauv cheeb tsam ze-infrared, lawv tuaj yeem siv tau zoo li qhov ze-infrared fluorescent probes rau kev tshuaj xyuas cov khoom tseem ceeb, thiab yog li tuaj yeem siv rau ze-infrared fluorescence immunoassay. , DNA sequencing thiab lwm yam frontier fields of life sciences.