Complexes of aryl-substituted porphyrins and naphthalenediimide (NDI): investigations by synchrotron X-ray diffraction and NMR spectroscopy

Abstract

New donor-acceptor hybrids of Zn(II)-metallated 5,15-diaryl porphyrins have been designed and synthesised via the porphyrin interactions with an electron acceptor molecule, di-n-hexyl N-substituted 1,2,4,8-naphthalenetetracarboxylic diimide (NDI). Binding interactions within these supramolecular complexes were investigated in the solid state by synchrotron X-ray diffraction and probed in solution by (1)H NMR spectroscopy. The systematic modulation of the porphyrin π-density was achieved, for the first time as multiple methoxy and fluorine groups were introduced as substituents to the 5,15-diaryls of the porphyrin. For these, the variation of the porphyrin-NDI binding strengths determined by (1)H NMR titrations was shown, using the Swain's type dual parameter approach, to be closely linked with the peripheral substitution pattern of the diaryl porphyrins validated by crystallography. The new 1:1 donor-acceptor complexes formed display characteristic features of the aromatic-stacked systems, i.e. the parallel arrangement and short interplanar separation between the substituted porphyrin and NDI. Synthetic modification of electron-density on the porphyrin surface by introducing substituents at peripheral sites of functionalised porphyrins represent a general solution towards electronically tunable aromatic surfaces: an understanding of their solution and solid state behaviour will significantly improve the rational design of new functional donor-acceptor supramolecular materials with potential applications ranging from new energy materials to dye-sensitised solar cells, photovoltaics and future drug delivery devices.

Thermally Reduced Graphene Oxide Nanohybrids of Chiral Functional Naphthalenediimides for Prostate Cancer Cells Bioimaging

“…[ 63 ] Values of K a 1:1 were found to range 13-110 M −1 for system involving NDI and Zn(II)metallated porphyrins. K a 1:1 of phenylalanine tagged NDIs D-3 , D-4 , D-5 , and D-6 reported in Table 3 are up to three orders of magnitude higher (K a ( 3 ) 1:1 = 1730 M −1 ) suggesting that coronene is a better guest system for NDIs in a supramolecular assembly in THF -toluene solutions.…”

Ambient Water‐Stable Dianionic Electron Donors: Intramolecular Noncovalent Conduits Assist Charge Delocalization

“…In addition, X‐ray data clearly established the effect of the additional two electrons of the dianion in altering the bond length of imide carbonyls, imide rings, and naphthalene ring compared to neutral NDI and cyano groups of tetracyanoquinodimethanes, respectively. The imide carbonyl bond lengths increase from 1.206–1.209 Å in the native NDI to 1.234–1.219 Å in C1−O1 and C5−O2 . In the imide rings, the bonds C1−N1 (1.385 Å), C1−C2 (1.454 Å), and C4−C5 (1.453 Å) undergo a decrease of up to 0.032 Å, with respect to the NDI.…”

Isolation of Tetracyano‐Naphthalenediimide and Its Stable Planar Radical Anion

“…Thestructural parameters are listed in Tables S2 and S3. [19] Such bond lengthening in 1C À is driven by the delocalization of the unpaired electron. Thei mide carbonyl (C=O) bond distances ranged between 1.222-1.228 ,w hile the cyano (CN) distances were between 1.140-1.150 .T he carbonyl bond distances of NDI radical anion (with no NDI core-substitution) were reported in the range of 1.218-1.234 .…”