Tight Electronic Coupling within Loosely Held Polyaromatic Cavities: Tris(N-Salicylideneaniline)-Derived Ligands and Receptors Dongwhan Lee Department of Chemistry, Indiana University Bloomington
[email protected] Dynamic 2-D Conjugation
Long Range Conformational Transmission
Structural distortion of planar conjugated systems can modify the effective conjugation “area” sampled by electrons and excitons.
t − αi e τi
OH
(1)
Global helicity predetermined by local chirality residing on 2˚ alcohol groups.
(1)
#$
···
∞
κ # kRET ∝ ΦD " FD(λ)εA(λ)λ4dλ κR2DA 6 0 τ D kRET ∝ ΦD J (λ) τD RDA 6 % & 2R −θDADA− 3cos J (λ)θDcos θA)2 kRET ∝κ2Kexp = (cos L " # κ2 kRET ∝ ΦD J (λ) τD RDA 6
Artificial systems displaying selfregulatory properties continue to remain an engaging challenge.
fl. intensity (a.u.)
n can be exploited as aβ[L] powerful θ= 2 signal amplification mechanism. 1 cos + β[L] θDA − 3cos θD θA)2n κ = (cos 2
Allosteric Switching
(2)
α2 = 0.03; 0.615 nsec " τ2 = # $ ∞ α1The = 0.97; nsec κτ12 = 0.160 orientation-dependent kRET α∝ = ΦD0.03; τ =6 0.608 nsec FD(λ)εA(λ)λ4dλ 2resonance τD R2DAenergy 0 transfer (RET)
"
OH Ph
KNF Model (sequential conformational transition)
τ1 = 0.170 nsec t τ2 = 0.615 nsec n − ! τ1 = 0.160 nsec τ αi e i I(t) = τ2 = 0.608 nsec
Signal-Amplifying i=1 β[L]n “Inverted Antenna” α1 = 0.97;θτ= 0.170 1= 1+ β[L]nnsec
OH
Ph
i=1
···
(2)
O
H O H
400
500
600
···
700
Wavelength (nm)
1
O + ne → R 1
···
α1 = 0.97; α2 = 0.03; α1 = 0.97; α2 = 0.03;
Ph
···
n !
OH
Mechanical coupling is a viable alternative for electronic coupling in long-range signal transmission.
···
I(t) =
Ph
