The photophysical properties of two supramolecular building blocks oc and oc2 consisting of a perylene bisimide chromophore substituted with either one or two calix [4]arene units in the N-imide position as well as those of the reference compound oref without calix[4]arene substituents were investigated. A complete picture of the processes taking place after photoexcitation in toluene, CH 2 Cl 2 , and benzonitrile was obtained by means of UV/vis absorption, steady state and time-resolved emission, and femtosecond transient absorption spectroscopy. It has been found that the fluorescence emission of compounds oc (Φ fl ) 0.03 in CH 2 Cl 2 ) and oc2 (Φ fl < 0.01 in CH 2 Cl 2 ) is almost completely quenched compared with the highly emissive reference compound oref (Φ fl ) 0.99 in CH 2 Cl 2 ) because of fast electron-transfer processes from the calix[4]arene moieties to the perylene bisimide chromophore. This predominantly takes place with rate constants of k CS ) 3 × 10 10 s -1 (τ CS ) 32 ps) for compound oc and k CS ) 9 × 10 10 s -1 (τ CS ) 11 ps) for compound oc2 (in CH 2 Cl 2 ) leading to a short-lived charge-separated state consisting of the reduced perylene bisimide unit and the oxidized calix[4]arene moiety.

We report on a series of bis-chromophoric compounds o2c, g2c, and r2c, afforded by linking two identical orange, green, or red perylene bisimide (PBI) units, respectively, through a calix[4]arene spacer unit. The PBI units are characterized by their increasing sterical demand from a planar conformation, which is orange (o) colored, via the slightly distorted greenish (g) colored form to the strongly distorted derivative, which is red (r) colored

The synthesis of multichromophoric perylene bisimide-calix[4]arene arrays with up to five perylene units (containing orange, violet, and green perylene bisimide chromophores) and of monochromophoric model compounds was achieved by subsequent imidization of mono-Boc functionalized calix[4]arene linkers with three different types of perylene bisimide dye units. The optical properties of all compounds were studied with UV/vis absorption and steady state and time-resolved fluorescence spectroscopy. Upon excitation of the inner orange dye at 490 nm of array 3, strong fluorescence emission of the outer green perylene bisimide (PBI) chromophore at 744 nm is observed. The fluorescence excitation spectra of compounds 3 and 4 (lambdadet = 850 nm) show all absorption bands of the parent chromophores (e.g., all perylene units contribute to the emission from S1 state of the green PBI). Thus, the fluorescence emission and excitation spectra as well as time-resolved data of fluorescence lifetimes in the absence (tauD = 5.1 ns) and in the presence of an acceptor (tauDA = 0.8 ns) suggest efficient energy transfer processes between the perylene bisimide dye units. For the bichromophoric array 4, the energy transfer rate is calculated to a value of 1.05 x 109 s-1. These results demonstrate highly efficient energy transfer in cofacially assembled dye arrays.

Perylene bisimide-calix [4]arene arrays composed of up to three different types of perylene bisimide chromophores (orange, red, and green PBIs) have been synthesized. Within these arrays, the individual chromophoric building blocks are positioned in defined spatial orientation and are easily replaceable by each other without influencing the overall geometric arrangement of the supramolecular system. The specific optical properties of the individual chromophore facilitated the investigation of photoinduced processes very accurately by time-resolved emission and femtosecond transient absorption spectroscopy. A quantitative analysis of the photophysical processes as well as their rate constants have been obtained by employing UV/vis absorption, steady state and time-resolved emission, femtosecond transient absorption spectroscopy, and spectrotemporal analysis of the femtosecond transient absorption data. These studies reveal very efficient energy transfer processes from the orange to the red PBI chromophoric unit (k ET ) 6.4 × 10 11 s -1 for array or), from the red to the green PBI (k ET ) 4.0 × 10 11 s -1 for array rg), and slightly less efficient from the orange to the green PBI (k ET ) 1.5 × 10 11 s -1 for array og) within these perylene bisimide-calix[4]arene arrays. The experimentally obtained rate constants for the energy transfer processes are in very good agreement with those calculated according to the Fo ¨rster theory.

The fluorescent dye 4-dimethylamino-1,8-naphthalimide was incorporated at the bay area of N,N'-bispyridyl perylene bisimide to afford a fourfold-functionalized perylene bisimide ligand. Through self-assembly directed by metal-ion coordination, a multichromophore supramolecular entity composed of sixteen dimethylaminonaphthalimide antennas and a perylene bisimide-walled square core was subsequently constructed from this linear ditopic ligand and 90 degrees metal corner [Pd(dppp)](OTf)2 (dppp=1,3-bis(diphenylphosphino)propane; OTf=trifluoromethanesulfonate) in good yield. The isolated metallosupramolecular square was characterized by elemental analysis and 1H, 13C, and 31P{1H} NMR and UV/Vis spectroscopy. Furthermore, by means of 1H NMR diffusion-ordered spectroscopy (DOSY) the dimension of this assembly was evaluated by employing a previously reported perylene bisimide ligand and its square assembly as references. The results obtained confirm the square framework of the current assembly. The optical properties of this multichromophore dye assembly were investigated by UV/Vis and steady-state and time-resolved fluorescence spectroscopy. It was revealed that light captured by dimethylaminonaphthalimide antennas could be efficiently transported to the perylene bisimide core by a fluorescence resonance mechanism (energy-transfer efficiency E=95%), and this resulted in almost exclusive detection of intense perylene bisimide emission, irrespective of the excitation wavelength applied. The present square scaffold containing aminonaphthalimide antenna dyes exhibits more than seven times higher fluorescence quantum yield (Phifl=0.37) than a previously reported pyrene-bearing perylene bisimide-walled square (Phifl=0.05). Thus, this multichromophore square assembly with aminonaphthalimide antenna dyes is an artificial model for the cyclic light-harvesting complexes in purple bacteria.