ABSTRACT
Chromophore Functional Group λmax/nm εmax λmax/nm εmax λmax/nm εmax Ether –O-185 1000 Thioether –S-194 4600 215 1600 Amine –NH2-195 2800 Amide –CONH2 <210 — Thiol –SH 195 1400 Disulfide –S-S-194 5500 255 400 Bromide –Br 208 300 Iodide –I 260 400 Nitrile –C≡N 160 — Acetylide (alkyne) –C≡C-175-180 6000 Sulfone –SO2-180 — Oxime –NOH 190 5000 Azido >C=N-190 5000 Alkene –C=C-190 8000 Ketone >C=O 195 1000 270-285 18-30 Thioketone >C=S 205 strong Esters –COOR 205 50 Aldehyde –CHO 210 strong 280-300 11-18 Carboxyl –COOH 200-210 50-70 Sulfoxide >S→O 210 1500 Nitro –NO2 210 strong Nitrite –ONO 220-230 1000-2000 300-4000 10 Azo –N=N-285-400 3-25 Nitroso –N=O 302 100 Nitrate –ONO2 270 (shoulder) 12 Conjugated hydrocarbon –(C=C)2-(acyclic) 210-230 21 000 Conjugated hydrocarbon –(C=C)3-260 35 000 Conjugated hydrocarbon –(C=C)4-300 52 000 Conjugated hydrocarbon –(C=C)5-330 118 000 Conjugated hydrocarbon –(C=C)2-(alicyclic) 230-260 3000-8000 Conjugated hydrocarbon C=C-C≡C 219 6500 Conjugated system C=C-C=N 220 23 000 Conjugated system C=C-C=O 210-250 10 000-20 000 300-350 weak Conjugated system C=C-NO2 229 9500 Phenyl 184 46 700 202 6900 255 170
Naphthalene 220 112 000 275 5600 312 175
Anthracene 252 199 000 375 7900
Pyridine N
174 80 000 195 6000 251 1700
Quinoline
N
227 37 000 270 3600 314 2750
Isoquinoline N
218 80 000 266 4000 317 3500
Heteroannular diene + 0 Homoannular diene +39 Extra double bond +30 Alkyl substituent or ring residue +5 Exocyclic double bond +5 Polar groups: –OOCR +0 –OR +6 –S-R +30 halogen +5 –NR2 +60 λ Calculated = Total
Increments for each (in nm): Heteroannular diene +0 Homoannular diene +39 Double bond +30 Alkyl group: α-+10 β-+12 γ-and higher +18 Polar groups: –OH α-+35 β-+30 δ-+50 –OOCR α, β, γ, δ +6 –OR α-+35 β-+30 γ-+17 δ-+31 –SR β-+85 –Cl α-+15 β-+12 –Br α-+25 β-+30 –NR2 β-+95 Exocyclic double bond +5 λ Calculated = Total
Substituent Increment (in nm) –R –4 –COR –4 –CHO 0 –OH –16 –OR –16 –COOR –16
Increment (in nm) Substituent o-m-p-–R +3 +3 +10 –COR +3 +3 +10 –OH +7 +7 +25 –OR +7 +7 +25 –O-+11 +20 +78 (variable) –Cl +0 +0 +10 –Br +2 +2 +15 –NH2 +13 +13 +58 –NHCOCH3 +20 +20 +45 –NHCH3 — — +73 –N(CH3)2 +20 +20 +85
