Synthesis and study of complex formation of tri-and tetranitro-9-fluorenone oximes with 3d metals: Crystal and molecular structure of the 1: 1 solvate of 2,4,5,7-tetranitro-9-fluorenone oxime with acetonitrile

2,4,5,7‐Tetranitrofluorenone Oximate for the Naked‐Eye Detection of H‐Bond Donors and the Chiroptical Sensing of Enantiopure Reagents

“…In addition, we imagined that this topic was an opportunity to associate molecular recognition, supramolecular stereocontrol and chiroptical studies (Scheme 1, B ). In fact, as repulsions between neighboring nitro groups at positions 4 and 5 of 1 were bound to occur, [11] atropisomeric M and P conformations were likely to form in solid and solution states. Then, with rapidly interconverting helical geometries, chiral recognition events could be probed with enantiopure analytes (Scheme 1, B ).…”

“…This immediate proximity of the polar moieties led us to investigate possible steric and electronic repulsions and the subsequent occurrence of a twist (curvature) of the overall molecular framework. This was first tackled by solid‐state analyses of published 3 (CCDC 681251) [11] and novel [Me 4 N][ 1 ] salt (Figure 4). [21] These structures, revealed a twist around the central five‐membered ring and a definite bending of the tricycle by repulsion of the two nitro groups (intramolecular N⋅⋅⋅N distance 3.06(7) Å).…”

“…A straightforward synthesis of 1 was carried out as outlined in Scheme 2. Condensation of tetranitrofluorenone 2 [6b] with hydroxylamine hydrochloride afforded oxime 3 [11] in excellent isolated yield (94 %). [16] Then, various ion pairs were prepared by quantitative reactions with hydroxide/methoxide bases to afford the sodium, tetramethylammonium and tetrabutylammonium salts, namely [Na] [1], [Me 4 N] [1] and [Bu 4 N] [1].…”