T‐Shaped (Donor–π–)₂Acceptor–π–Donor Push–Pull Systems Based on Indan‐1,3‐dione

Abstract

Sixteen model (donor-π-) 2 acceptor-π-donor [(D-π-) 2 A-π-D] molecules with an extraordinary T-shaped arrangement were designed and synthesized. Indan-1,3-dione was employed as a central acceptor with electron donors linked at the C-2, C-4, and C-7 positions. These push-pull molecules represent a first systematic modification of an indan-1,3-dione-fused benzene ring. The structures and properties of all target molecules were investigated by X-ray analysis, electrochemistry, UV/Vis absorption spectroscopy, differential scanning calorimetry, electric-field-induced second-harmonic generation (EFISHG) studies, and DFT calculations. A thorough evaluation of all of the gathered data has been performed,

From Linear to T‐Shaped Indan‐1,3‐dione Push–Pull Molecules: A Comparative Study

“…The position of the indan‐1,3‐dione moiety in 3 and 4 is almost perfectly co‐planar with the peripheral aromatic rings (see the inset in Figure ). This is in contrast to the previously published X‐ray analyses of the derivatives without an additional triple bond linker . However, the averaged quinoid character ( δr ) and the Bird index ( I 6 ) of the peripheral DMA rings in 3 were calculated to be 0.01 and 87.8.…”

“…C(2)‐Unsubstituted chromophores 1 – 3 were prepared by Suzuki – Miyaura or Sonogashira cross‐coupling reactions between 4,7‐diiodoindan‐1‐3‐dione ( 9 ) and boronic acid pinacol esters 10 or 11 or 4‐ethynyl‐ N , N ‐dimethylaniline ( 12 ) under standard conditions in satisfying yields 62 – 72%. T‐shaped chromophores 5 – 7 were prepared from the corresponding molecules 1 – 3 , and N , N ‐dimethylanilino (DMA) substituted propargyl aldehyde 13 utilizing Al 2 O 3 ‐catalyzed Knoevenagel condensation in moderate 51 – 70% yields .…”

“…Various push–pull chromophores adopting rather unique spatial arrangements such as H‐, L‐, T‐, V‐, X‐, and Y‐shapes have been reported so far . Accordingly, we have recently designed and synthesized a new class of T‐shaped molecules based on indan‐1,3‐dione . Within these first reports, we have demonstrated the first utilization of indan‐1,3‐dione as a central acceptor unit through its modification not only at C(2) position, but also at positions C(4) and C(7) of the fused benzene ring.…”

Synthesis and properties of push-pull imidazole derivatives with application as photoredox catalysts

“…However, thiophene can be polarized even further by connecting amino donor and indan-1,3-dione acceptor as we have recently demonstrated for T-shaped push-pull molecules (I5 = 58). 44 The supramolecular arrangement of 3 reveals head to tail chromophore arrangement and 2D-layered array structures with π-π stacking typical for dipolar D-π-A molecules. Thermal stability.…”

“…Considering (5-methoxy)thienyl ring as a "rotating" substituent, larger Stokes shift (>5.000 cm -1 ) implies higher geometry reorganization of 2 and 3 upon photoexcitation. 44 The excited state energies (E0,0) referring to the transition between the lowest vibrational states of the first excited and ground levels S1 and S0 were further derived from the absorption and fluorescence spectra (Table 1). These data fall within the range of know values for cyanoarenes (2.90-4.01 eV); 1 however, the calculated E0,0 values of DCI derivatives 2 and 3 are ≥1 eV higher than that of DCP derivative 1.…”