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Indanone-containing scaffolds are attractive synthetic targets because of their wide occurrence in many natural products, drugs and functional materials. In the last few years, enormous efforts have been devoted for...

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Single‐crystal X‐ray diffraction studies of two terminally protected tetrapeptides Boc‐Ile‐Aib‐Val‐m‐ABA‐OMe (I) and Boc‐Ile‐Aib‐Phe‐m‐ABA‐OMe (II) (Aib=α‐aminoisobutyric acid; m‐ABA=meta‐aminobenzoic acid) reveal that they form continuous H‐bonded helices through the association of double‐bend (type III and I) building blocks. NMR Studies support the existence of the double‐bend (type III and I) structures of the peptides in solution also. Field emission scanning electron‐microscopic (FE‐SEM) and high‐resolution transmission electron‐microscopic (HR‐TEM) images of the peptides exhibit amyloid‐like fibrils in the solid state. The Congo red‐stained fibrils of peptide I and II, observed between crossed polarizers, show green‐gold birefringence, a characteristic of amyloid fibrils.

Synthesis of fluorescent molecules has drawn considerable attention due to their potential applications in life and material sciences. Here we report a metal‐free approach to a new class of fluorophore, namely, 6‐(2‐hydroxyaryl)isoindolo[2,1‐a]quinoxalin‐11(5H)‐ones exploiting ninhydrin ring system via base promoted tandem cyclization. The readily obtainable phenolic adducts of ninhydrin undergoes smooth reaction with o‐phenylenediamine in refluxing ethylene glycol/Et3N via breaking of C−C bond, N‐insertion, followed by heterocyclization to furnish the fully unsaturated isoindoloquinoxaline framework. Structures of the products are in good agreement with their IR, 1H NMR, 13C NMR, and mass spectral data. The photophysical properties of the synthesized compounds were studied by UV‐vis absorption and fluorescence spectroscopic techniques under ambient conditions, and the results reveal an interesting property of large Stokes shift.