Light‐Harvesting Metallosupramolecular Squares Composed of Perylene Bisimide Walls and Fluorescent Antenna Dyes

Abstract

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.

Supramolecular Coordination: Self-Assembly of Finite Two- and Three-Dimensional Ensembles

“…Notably, Würthner et al have designed light-harvesting metallosupramolecular squares having of perylene bisimide walls and fluorescent antenna dyes. 241 The fluorescent dye 4-dimethylamino-1,8-naphthalimide was incorporated at the bay area of N,N’-bispyridyl perylene bisimide ligand. Subsequent assembly of this ditopic ligand with [Pd(dppp)(OTf) 2 ] gave a self-assembled molecular square.…”

Photochemical Conversion of Solar Energy

“…[128] Light harvesting has also been investigated in a variety of other systems such as multichromophoric cyclodextrins, [129] phthalocyanines, [130] metallosupramolecular squares, [131] rotaxanes, [132] and polyelectrolytes. [133] A combination of self-organizing biological structures and synthetic building blocks has been used as a flexible method for the construction of antenna systems.…”

Self‐Assembly of Bis(merocyanine) Tweezers into Discrete Bimolecular π‐Stacks

“…49 g, 5.83 mmol, 70 % 22,H 7.07,N 4.68;found: C 72.14,H 7.03,N 4.71. N,bis(methylene)]bis(2-cyanoacetamide) (11): In an argon-flooded flask, the Cbz-protected diamine 10 (3.0 g, 5.01 mmol) was dissolved in a mixture of EtOAc (120 mL) and MeOH (60 mL) and the solution was degassed by applying a vacuum and flooding with argon. Pd/C (10 %, 100 mg) was then added to the solution and H 2 gas was supplied by means of a balloon.…”

“…[11] There has been considerable interest in the self-assembly of merocyanine dyes, [12][13][14][15] a class of chromophores with promise for nonlinear optical and photorefractive applications due to their outstanding dipolar and polarizability properties. [16] Moreover, we have recently shown merocyanines to be excellent p-type semiconducting absorber materials in organic bulk heterojunction solar cells.…”