The crystal and molecular structure of 3‐aminophthalhydrazide (Luminol)

Abstract

The crystal structure of 2‐aminophthalhydrazide (luminol) has been determined by X‐ray diffraction analysis. The space group determined was P&1macr; (No. 2) with cell constants of a = 12.714 Å, b = 14.132 Å. c = 7.1027 (Å), α = 101.24°, β = 94.84° and γ = 116.60° with six molecules per unit cell of formula molecular weight 177.16. The three luminol molecules form a hydrogen bonded trimeric unit. There is one intramolecular hydrogen bond per luminol molecule involving the NH2 group and the adjacent carbonyl group. All other hydrogen bonds are intermolecular. – Luminol crystallizes as amide‐hydroxyimunol tautomer. The protonated carbonyl group acts as hydrogen bond donor to a neightbouring unprotonated carbonyl group.

Hierarchical Assembly of a Phthalhydrazide‐Functionalized Helicene

“…In order to construct such a system, we chose a disk-shaped trimer formation of phthalhydrazide units, in which the resulting trimeric disk is known to assemble into 1D structures. [5,6] Rational introduction of a helicene moiety into the phthalhydrazide unit would lead to a new supramolecular assembly of helicenes, which would exhibit intriguing chirooptical properties. Herein we report a new helicene 1 that bears a phthalhydrazide unit as a multiple-hydrogenbonding site (Scheme 1).…”

Behind Crime Scenes: The Crystal Structure of Commercial Luminol

“…A phase pure crystalline powder of luminol form I could be obtained by slow cooling of an ethanol–water solution of luminol (3:1, vol %:vol %) from 80 °C to RT. As already mentioned, Paradies was able to solve and refine the single crystal structure of form I determined at LT . Starting with his coordinates, the crystal structure was refined with RT PXRD data to assist comparison of crystal structures of form I and II.…”

“…Despite its long history, the first crystal structure of neutral luminol was reported as late as in 1992 by Paradies . Suitable crystals for single crystal X-ray diffraction at low temperature (173 K; LT) could be obtained by controlled sublimation and were grown at 180 °C and at 5 Torr vacuum pressure in a closed environment on a cooling finger kept at 20 °C .…”

“…Despite its long history, the first crystal structure of neutral luminol was reported as late as in 1992 by Paradies . Suitable crystals for single crystal X-ray diffraction at low temperature (173 K; LT) could be obtained by controlled sublimation and were grown at 180 °C and at 5 Torr vacuum pressure in a closed environment on a cooling finger kept at 20 °C . The crystal structure revealed that luminol in the bulk structure is present not as the commonly reported amide–amide form (Figure a), but as amide–hydroxyimine tautomeric form (Figure b).…”

“… The structure of the commercial polymorph (form II) of 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol) used for ages by crime scene investigators to secure blood evidence was determined by powder X-ray diffraction and Rietveld refinement. The “new” form II is a polytype of form I . The two polymorphs only differ in distinct π-stacking motifs.…”