9,10-Phenanthrenequinone(PQ)andbenzilareimportantα-diketones.ThismanuscriptexplainsthefirstcomparisonofPQandbenzilmolecularproperties.Wehaveused1HNMR,13CNMR,1H-1HCOSY,HMBC,HMQC,UV-Visabsorptionandemission,CVandTGAexperimentstostudyPQandbenzilthatprovidedthefollowingnovelresults.(1)The1HNMR(CDCl3)ofPQshowδ8.19(H1),8.02(H4),7.72(H3),7.47(H2)insteadofanearlierreportedδ8.25(H4),8.08(H1),7.80(H2),7.55(H3);(2)inthe13CNMR(CDCl3),theC9/C10(C=O)signalofPQappearsupfield(δ180.3)comparedtoC9/C10(C=O)signalofbenzil(δ194.5),whichshowshigherelectrophiliccharacter(moreattractivefornucleophiles)ofC9/C10(C=O)ofbenzil;(3)thefirstλmaxfortheUV-VisabsorptionandemissionofPQareblue-shiftedcomparedtobenzildespiteincreasedconjugationattributedtothedifferentsymmetries(C2vforPQandC2hforBenzil)ofthetwomolecules;(4)theemissionspectrumofbenzilisbroadercomparedtothatofPQduetoslowerrelaxationoftheexcitedstate;(5)TheCVstudyshowsthatPQandbenzilaregoodelectronacceptorsandPQshowsabetterreductionprocessthanbenzilduetoanextraringthatprovidesstabilityforthereducedspecies(monoordiradicalanions);(6)TGAshowsthehigherthermalstabilityofPQthanbenzilattributedtothepresenceofphenanthreneunitinPQ.
