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Reported herein is the high yielding synthesis of a new fluorenone-based triazolophane and its sensing capabilities for polycyclic aromatic hydrocarbons (PAHs) and fluoride anions. Fluorescence, UV/Vis and 1H NMR spectroscopy results showed the triazolophane has a high sensitivity for selected PAHs and binds the fluoride anion in a 2 : 1 stoichiometry via C–H hydrogen bonding with the triazole and fluorenone protons.

Diiminoisoindoline (DII) can be modified with primary amines to afford bis-substituted heterocycles. Although the metal binding chemistry of isoindoline-based macrocycles and chelates has been explored, the corresponding chemistry of hydrocarbon substituted diiminoisoindolines remains open. The reaction of the bis(benzylimino)isoindoline with AgNO3 affords a Ag6 cluster complexed by four equivalents of ligand. The cluster exhibits a previously unknown argentophilic geometry. The Ag6 unit forms a compressed hexagon, comprised of two Ag3 triangles that are linked together to form a parallelogram. The argentophilic interactions range from ~ 2.76 to ~ 3.17 A.

A study of the transition metal chemistry with the planar tridentate ligand 2,6-diacetylpyridine dihydrazone (1, DAPH) is presented, expanding the chemistry of this ligand across the first row of the transition metals. Ligand 1 forms both 1:1 and homoleptic 2:1 complexes with transition metal ions, depending on the metal salt used and reaction conditions, and seven new complexes with Mn, Fe, Co, Cu and Zn are presented. All compounds, including the ligand, have been characterized by X-ray crystallography. DAPH (1) binds to metal ions in an asymmetric fashion, with a M–Npyr bond that is shorter than the flanking M–Nimine bonds. Additionally, the Nimine–M–Nimine bonds form acute angles ranging from ~ 140 to 160°, depending on the identity of the metal ion and ligand environment. All compounds are compared with previously elucidated DAPH structures from the literature.

The new fluorescent chromophore BOPHY can be readily synthesized in two steps from commercially available reagents via the coupling of pyrrole-2-carboxaldehyde with hydrazine followed by reaction with BF3. The resultant symmetric and dimeric tetracycle is composed of two BF2 units in six-membered chelate rings appended with pyrrole units on the periphery. The quantum yields of fluorescence for the unmodified compound and the tetramethyl variant are near unity, with values of 95 and 92%, respectively, in CH2Cl2. We have probed the electronic structure of this compound via cyclic voltammetry and density functional theory analysis.

In this Letter, we present a synthetic and structural study into bis-imino substituted diiminoisoindolines, which can be synthesized either via CaCl2 mediated reaction of phthalonitrile with primary amines, or via direct reaction of these amines with unsubstituted diiminoisoindoline. The preferred synthesis does depend on the methodology, and in two cases singly substituted adducts were formed. The single crystal X-ray structures show that, with the exception of the bis-naphthyl compound, the anti conformation is preferred, and that the ionizable hydrogen atom resides on an exocyclic nitrogen rather than the central isoindoline nitrogen atom.

This report presents the single crystal X-ray structures of several substituted isoindolines that have been frequently used as starting materials for phthalocyanines, phthalocyanine analogs and related chelates. The structures of 1,3-diiminoisoindoline (1), 1,3-bis(hydroxyimino)isoindoline (2), 1,4-diaminophthalazine (3), 1,1,3-trichloroisoindoline (4) and 3-imino-1-oxoisoindoline (5) are reported; compounds 2 and 3 are synthesized from diiminoisoindoline (1) and 4 and 5 are produced from phthalimide. All five compounds are planar macrocycles, and localization of double bonds can be readily determined. We elucidated one of the known structures of 1 at low temperature, and observed two additional new structures of 1. For the crystal forms of 1 and compounds 2, 3, and 5, hydrogen bonding in the solid state was observed. Compounds 1, 2 and 3 form extended hydrogen bonded arrays in the solid state, whereas 5 forms discrete hydrogen bonded dimers.

The reaction of diiminoisoindoline with amine-terminated polyethers results in the formation of phthalocrown macrocycles. For n = 1 (where n is the number of ether units), a 2 + 2 condensation takes place, but for n = 2 and 3, a 1 + 1 macrocycle formation occurs. The n = 2 phthalocrown is particularly stable due to a strong intramolecular hydrogen bond, but the n = 3 ring hydrolyzes to form a 3-imino-1-oxoisoindoline derivatized crown ether species. For the n = 1 phthalocrown, we observed dynamic behavior in the (1)H NMR spectrum, and using VTNMR were able to measure a ΔG(‡) = 44.6 kJ/mol for proton exchange.