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Crystalline adducts of some substituted salicylic acids with 4-aminopyridine, including hydrates and solvates: contact and separated ionic complexes with diverse supramolecular synthons

Crystalline adducts of some substituted salicylic acids with 4-aminopyridine, including hydrates and solvates: contact and separated ionic complexes with diverse supramolecular synthons
Crystalline adducts of some substituted salicylic acids with 4-aminopyridine, including hydrates and solvates: contact and separated ionic complexes with diverse supramolecular synthons
Co-crystallizations of some 3, 5 and 6 mono-substituted salicylic acids with 4-aminopyridine, using a variety of solvents, have yielded a number of new complex solid forms, mainly with the 5-halide-substituted acid, including some hydrates and solvates. In all cases, proton transfer occurs from the carboxyl group of the acid to the pyridine nitrogen of the base, with the COO?H+NPy synthon being found in 12/14 cases. The prime exception is 4-aminopyridinium:5-aminosalicylate:pyridine solvate, where the carboxylate group forms a 2-point synthon with one hydrogen of the 4-amino group on the aminopyridinium supplemented by a C–HO interaction involving an ortho hydrogen. This synthon is also found as one component of a disordered structure of the 4-aminopyridinium:5-chlorosalicylate. The other component adopts the normal pyridiniumcarboxylate synthon. The adoption of 2-point or 1-point synthons, and the geometry of the former, is influenced by the presence of other hydrogen-bonding interactions involving hydrate water molecules or the amine of the 4-aminopyridinium group. A detailed packing analysis shows a number of similarities, partly linked to the synthon geometries. The structures generally fall into two groups, one derived from a simple zero-dimensional pyridinium–carboxylate monomer construct, the other from a zero-dimensional pyridinium–carboxylate centrosymmetric dimer construct. The former group contains most of the hydrates and the latter all of the 5-halide and methyl anhydrates, plus the 5-I pyridine solvate. The diversity of structures found confirm the frequent unpredictability in the structures adopted by products of co-crystallizations when ionic forms are produced.
1466-8033
7466-7478
Montis, Riccardo
11e15e46-6671-4ed0-9457-db82828bcdc7
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Montis, Riccardo
11e15e46-6671-4ed0-9457-db82828bcdc7
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da

Montis, Riccardo and Hursthouse, Michael B. (2012) Crystalline adducts of some substituted salicylic acids with 4-aminopyridine, including hydrates and solvates: contact and separated ionic complexes with diverse supramolecular synthons. CrystEngComm, 14 (21), Summer Issue, 7466-7478. (doi:10.1039/C2CE26008E).

Record type: Article

Abstract

Co-crystallizations of some 3, 5 and 6 mono-substituted salicylic acids with 4-aminopyridine, using a variety of solvents, have yielded a number of new complex solid forms, mainly with the 5-halide-substituted acid, including some hydrates and solvates. In all cases, proton transfer occurs from the carboxyl group of the acid to the pyridine nitrogen of the base, with the COO?H+NPy synthon being found in 12/14 cases. The prime exception is 4-aminopyridinium:5-aminosalicylate:pyridine solvate, where the carboxylate group forms a 2-point synthon with one hydrogen of the 4-amino group on the aminopyridinium supplemented by a C–HO interaction involving an ortho hydrogen. This synthon is also found as one component of a disordered structure of the 4-aminopyridinium:5-chlorosalicylate. The other component adopts the normal pyridiniumcarboxylate synthon. The adoption of 2-point or 1-point synthons, and the geometry of the former, is influenced by the presence of other hydrogen-bonding interactions involving hydrate water molecules or the amine of the 4-aminopyridinium group. A detailed packing analysis shows a number of similarities, partly linked to the synthon geometries. The structures generally fall into two groups, one derived from a simple zero-dimensional pyridinium–carboxylate monomer construct, the other from a zero-dimensional pyridinium–carboxylate centrosymmetric dimer construct. The former group contains most of the hydrates and the latter all of the 5-halide and methyl anhydrates, plus the 5-I pyridine solvate. The diversity of structures found confirm the frequent unpredictability in the structures adopted by products of co-crystallizations when ionic forms are produced.

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Published date: 13 August 2012
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow, Chemistry, Faculty of Natural and Environmental Sciences

Identifiers

Local EPrints ID: 352877
URI: http://eprints.soton.ac.uk/id/eprint/352877
ISSN: 1466-8033
PURE UUID: 70bdeffd-eabc-48b1-91b1-8519d1af563e

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Date deposited: 21 May 2013 14:04
Last modified: 14 Mar 2024 13:57

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Author: Riccardo Montis

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