Table 1 Absorption and emission maxima and electrochemistry of the investigated heteroacenes.

From: Effects of electronegative substitution on the optical and electronic properties of acenes and diazaacenes

Acene

11a

11b

11c

15a

15b

15c

16a

16b

16c

X=

H

Cl

CN

H

Cl

Br

H

Cl

CN

λmax abs (nm)

571

617

—

692

756

759

—

—

—

ϵmax (103 M−1 cm–1)

22.7

17.3

—

19.1

12.9

10.2

—

—

—

λmax abs,ss (nm) [cm−1]*

573 [79]

636 [484]

—

737 [892]

806 [821]

ND

—

—

—

λmax emission (nm)

582

635

—

713

Non-fluorescent

Non-fluorescent

—

—

—

Quantum yield Φ

0.09

0.02

—

<0.01

—

—

—

—

—

E1/20/−(V)†

−1.19

−0.92

—

−1.05

−0.79

−0.79

—

—

—

E1/2+/0 (V)†

+0.99

+1.11

—

+0.68

+0.83

+0.80

—

—

—

Elchem. gap (V)

2.18

2.03

—

1.73

1.62

1.59

—

—

—

Opt. gap (eV)†

2.17

2.01

—

1.79

1.64

1.63

—

—

—

S1vert§

2.07

1.91

1.38

1.58

1.44

ND

2.16

2.13

1.61

calcd. HOMO-LUMO gap (eV)∥

2.37

2.25

1.81

1.87

1.77

ND

2.41

2.39

2.00

HOMO (eV)

−5.72

−6.03

−6.66

−5.37

−5.66

ND

−5.28

−5.68

−6.38

LUMO (eV)

−3.35

−3.78

−4.84

−3.50

−3.89

ND

−2.87

−3.30

−4.38

  1. *Solid state absorption in thin films. The values in square brackets are the shifts observed when going from solution into thin solid films.
  2. †From absorption maxima.
  3. ‡In a 1:1 (v/v) mixture of a 0.1 M acetonitrile solution of nBu4NPF6 and toluene, vs FeCp2+/0.
  4. sect;TD-DFT calculations at the B3LYP/6-311+G* level. The transitions are all one-electron transitions with a >80% HOMO-LUMO contribution.
  5. ∥The desilylated model compounds 11a′, 11b′, 15a′ and 15b′ were used for the calculations to reduce the computation time. DFT B3LYP/6-311+G*/6-311+G* method was used.
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