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Shemchuk O, André V, Duarte MT, Braga D, Grepioni F. Mechanochemical preparation of molecular and ionic co-crystals of the hormone melatonin. CrystEngComm 2019. [DOI: 10.1039/c9ce00316a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular and ionic co-crystals of melatonin with piperazine, DABCO and CaCl2 were obtained via kneading with ethanol: the solubility of melatonin in H2O increases by an order of magnitude when combined with CaCl2.
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Affiliation(s)
- O. Shemchuk
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
| | - V. André
- Centro de Química Estrutural
- Instituto Superior Técnico
- 1049-001 Lisboa
- Portugal
| | - M. T. Duarte
- Centro de Química Estrutural
- Instituto Superior Técnico
- 1049-001 Lisboa
- Portugal
| | - D. Braga
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
| | - F. Grepioni
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
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Grepioni F, Braga D, Chelazzi L, Shemchuk O, Maffei P, Sforzini A, Viscomi GC. Improving solubility and storage stability of rifaximin via solid-state solvation with Transcutol®. CrystEngComm 2019. [DOI: 10.1039/c9ce00567f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Crystallization of rifaximin from Transcutol® affords the new anhydrous τ-form, which combines a high dissolution rate with a high storage stability, as it is not affected by exposure to humidity.
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Affiliation(s)
- F. Grepioni
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
| | - D. Braga
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
| | - L. Chelazzi
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
| | - O. Shemchuk
- Molecular Crystal Engineering Laboratory
- Dipartimento di Chimica “G. Ciamician”
- Università di Bologna
- 40126 Bologna
- Italy
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Shemchuk O, Braga D, Grepioni F. Alloying barbituric and thiobarbituric acids: from solid solutions to a highly stable keto co-crystal form. Chem Commun (Camb) 2018; 52:11815-11818. [PMID: 27722256 DOI: 10.1039/c6cc06615a] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alloying isomorphous crystals of barbituric acid (BA) and thiobarbituric acid (TBA) yields solid solutions of general formula BAxTBA1-x (x < 0.8); for x = 0.5 the stable co-crystal BA0.5TBA0.5, isomorphous with the parent keto forms, is observed, which melts at 265 °C, i.e. ca. 10 and 20 °C higher than the melting points of BA and TBA, respectively. While the BAxTBA1-x solid solutions with x > 0.5 are stable, those with x < 0.5 convert, with time or temperature, to the BA0.5TBA0.5 co-crystal.
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Affiliation(s)
- O Shemchuk
- Dipartimento di Chimica Giacomo Ciamician, Università degli Studi di Bologna, Via Selmi 2, 40126 Bologna, Italy.
| | - D Braga
- Dipartimento di Chimica Giacomo Ciamician, Università degli Studi di Bologna, Via Selmi 2, 40126 Bologna, Italy.
| | - F Grepioni
- Dipartimento di Chimica Giacomo Ciamician, Università degli Studi di Bologna, Via Selmi 2, 40126 Bologna, Italy.
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Abstract
Ionic co-crystals (ICCs) of l- and dl-histidine with CaCl2, CaBr2 and CaI2 were prepared by mechanochemical and solution methods and were structurally characterized by either single crystal or powder X-ray diffraction methods.
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Affiliation(s)
- O. Shemchuk
- Dipartimento di Chimica “Giacomo Ciamician”
- Università degli Studi di Bologna
- 40126 Bologna
- Italy
| | - L. Degli Esposti
- Institute of Science and Technology for Ceramics (ISTEC)
- National Research Council (CNR)
- 48018 Faenza (RA)
- Italy
| | - F. Grepioni
- Dipartimento di Chimica “Giacomo Ciamician”
- Università degli Studi di Bologna
- 40126 Bologna
- Italy
| | - D. Braga
- Dipartimento di Chimica “Giacomo Ciamician”
- Università degli Studi di Bologna
- 40126 Bologna
- Italy
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Romasanta AKS, Braga D, Duarte MT, Grepioni F. How similar is similar? Exploring the binary and ternary solid solution landscapes of p-methyl/chloro/bromo-benzyl alcohols. CrystEngComm 2017. [DOI: 10.1039/c6ce02282k] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maini L, Braga D, Grepioni F, Lampronti GI, Gaglioti K, Gobetto R, Chierotti MR. From isomorphous to “anisomorphous” ionic co-crystals of barbituric acid upon dehydration and return. CrystEngComm 2016. [DOI: 10.1039/c6ce00566g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Duarte MT, André V, Grepioni F, Rodriguez-Hornedo N, Maheshwari C. Synthon competition in new pharmaceutical forms: how crystal structure affects properties. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311090817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Chelazzi L, Grepioni F, Braga D. Solid-state synthesis and structure solution of chiral co-crystals and salts. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311090349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Lampronti GI, Maini L, Turrina A, Capucci D, Grepioni F, Braga D, Cuocci C, Chierotti MR, Gobetto R, Griesser UJ. Ionic co-crystals of active pharmaceutical ingredients and their applications in the pharmaceutical industry. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311090854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Viscomi GC, Campana M, Barbanti M, Grepioni F, Polito M, Confortini D, Rosini G, Righi P, Cannata V, Braga D. Crystal forms of rifaximin and their effect on pharmaceutical properties. CrystEngComm 2008. [DOI: 10.1039/b717887e] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- E. A. Marseglia
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, UK
| | - F. Grepioni
- Dipartimento di Chimica, Università di Sassari, Via Vienna 2, 07100, Sassari, Italy
| | - E. Tedesco
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, UK
| | - D. Braga
- Dipartimento di Chimica ``G. Ciamician”, Universita′ di Bologna, Via Selmi 2, 40126, Bologna, Italy
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Grepioni F, Curzi M, Lusi M, Braga D. Mechanically induced reactivity of molecular crystals: chemistry (almost) without solvents. Acta Crystallogr A 2005. [DOI: 10.1107/s010876730509536x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Braga D, Cojazzi G, Emiliani D, Maini L, Grepioni F. Reversible trapping of acid and base vapours into an amphoteric crystalline material. Chem Commun (Camb) 2001:2272-3. [PMID: 12240146 DOI: 10.1039/b106984e] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exposure of the solid zwitterion [CoIII(eta 5-C5H4CO2H)(eta 5-C5H4CO2)] to hydrated vapours of volatile acids (HCl, CF3CO2H, HBF4) or bases (NH3, NMe3, NH2Me) quantitatively produces the corresponding salts; the heterogeneous reactions are fully reversible, as the acid or base molecules can be removed by thermal treatment, regenerating the starting material.
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Affiliation(s)
- D Braga
- Dipartimento di Chimica G. Ciamician, University of Bologna, Via Selmi 2, 40126 Bologna, Italy.
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Abstract
The (-)O-H...O(-) interaction formed by the anions HCO3-, HCO4, HC4O4 and HC5O5- (HA-), obtained upon monodeprotonation of the corresponding carbonic, oxalic, squaric and croconic acids (H2A), has been investigated theoretically and experimentally. The ring (RING) and chain (CHAIN) hydrogen bond motifs established between these anions have been analysed in terms of geometry and energy and their occurrence in crystalline salts investigated by searching the Cambridge Structural Database (CSD) and the Inorganic Chemistry Structural Database (ICSD). It has been shown that hydrogen carbonates form RINGs, with the notable exception of NaHCO3, while only CHAINs are known for hydrogen oxalates. Hydrogen squarates and hydrogen croconates can form both RINGs and CHAINs. The structures of Rb- and Cs- hydrogen croconates, which present the two alternative motifs, have been discussed together with that of the hydrated salt NaHC5O5.H2O. The relationship between RING and CHAIN has been examined in the light of ab initio calculations. A rigorous quantum chemical study of the nature of the interanionic (-)O-H...O(-) interaction in both vacuum and condensed phase has shown that the interaction energy is dominated by the electrostatic component which becomes attractive at short O...O distances (less than 2.5 A) if the net ionic charge on the anion is delocalised away from the -OH group. It has been demonstrated that the RING motif is slightly metastable with respect to dissociation in the gas phase, but becomes stable in the crystal owing to the influence of the Madelung field. However, the CHAIN motif is unstable both in the gas phase and in the crystal. It is argued that interanionic (-)O-H...O(-) interactions ought to be regarded as stabilising bonding interactions rather than proper intermolecular hydrogen bonds because the RING and CHAIN aggregates are not energetically stable on an absolute scale of bonding energy (i.e., in the absence of counterions). The presence of very short non-hydrogen-bridged O...O contacts resulting from charge compression of polyatomic anions bridged by alkali cations is also discussed.
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Affiliation(s)
- D Braga
- Department of Chemistry G. Ciamician Univeristy of Bologna, Italy.
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Abstract
It is shown that the water-soluble dicarboxylic cationic acid [(eta5-C5H4COOH)2Co(III)]+ (1) is an extremely versatile building block for the construction of organometallic crystalline edifices. Removal of one proton from 1 leads to formation of the neutral zwitterion [(eta5-C5H4COOH)(eta5-C5H4COO)Co(III)] (2), while further deprotonation leads to formation of the dicarboxylate monoanion [(eta5-C5H4COO)2Co(III)]- (3). Compounds 1. 2 and 3 possess different hydrogen-bonding capacity and participate in a variety of hydrogen-bonding networks. The cationic form 1 has been characterised as its [PF6]- and Cl- salts 1-[PF6] and 1-Cl.H2O, as well as in its co-crystal with urea, 1-Cl.3(NH2)2CO, and with the zwitterionic form 2, [(eta5-CH4COOH)(eta5-C5H4COO)Co(III)][(eta5-C5H4COOH)2Co(III)]+[PF6]-, 2.1-[PF6]. The neutral zwitterion 2 behaves as a supramolecular crown ether: it encapsulates the alkali cations K+, Rb+ and Cs+ as well as the ammonium cation NH4+ in cages sustained by O-H...O and C-H...O hydrogen bonds to form co-crystalline salts of the type 2(2)-M[PF6] (M = K, Rb, Cs) and 2(2)-[NH4][PF6]. The deprotonated acid 3 has been characterised as its Cs+ salt, Cs+-3.3H2O.
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Affiliation(s)
- D Braga
- Dipartimento di Chimica G. Ciamician, Università di Bologna, Italy.
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Abstract
The utilization of noncovalent interactions to construct molecular crystals is evaluated in the context of inorganic and organometallic crystal engineering. The attention is focused on hydrogen-bonding interactions involving metal complexes in which the metal atoms participate in the bonding either directly or as ancillary systems. The role of ionic charges is discussed. It is shown, inter alia, that reproducible and transferable crystal synthesis strategies based on charge-assisted hydrogen bonds can be devised to build periodical supermolecules.
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Affiliation(s)
- D Braga
- Dipartimento di Chimica, Università di Sassari, Via Vienna 2, 07100 Sassari, Italy.
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Braga D, Maini L, Prodi L, Caneschi A, Sessoli R, Grepioni F. Anions derived from squaric acid form interionic pi-stack and layered, hydrogen-bonded superstructures with organometallic sandwich cations: the magnetic behaviour of crystalline. Chemistry 2000; 6:1310-7. [PMID: 10840952 DOI: 10.1002/(sici)1521-3765(20000417)6:8<1310::aid-chem1310>3.0.co;2-t] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Depending on the stoichiometric ratio, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione, H2SQA) reacts with [(eta6-C6H6)2Cr] in THF to form the crystalline material [(eta6-C6H6)2Cr][HSQA] (1) and in water to yield [[(eta6-C6H6)2Cr]2][SQA] x 6H2O (3); it also reacts with [(eta5-C5H5)2Co][OH] in water to form [[(eta5-C5H5)2Co]2][SQA] x 6H2O (4). Compound 1 is almost isostructural with the previously reported salt [(eta5-C5H5)2Co][HSQA] (2); its structure is based on pi-pi stacks between the benzene ligands and the hydrogen squarate anionic chains (pi-pi distance 3.375 A). Compounds 3 and 4 are isomorphous and have a structure in which layers of organometallic cations intercalate with layers of water molecules hydrogen bonded to squarate dianions. All crystals contain charge-assisted C-Hdelta+...Odelta- hydrogen bonds between the organometallic and the organic components, while negative O-H(-)...O(-) and O-H...O(2-) interactions are present in the pairs 1/3 and 2/4, respectively. In constrast to most organic salts of [(eta6-C6H6)2Cr]+ and [(eta5-C5H5)2Co]+ which are yellow, crystals of compounds 1-4 are orange. Reflectance spectra measured on the crystalline material 1 show the presence of an intense tail that can be assigned to a charge-transfer transition through the [(eta6-C6H6)2Cr]+/[HSQA]- pi-stacking interactions, while the pi stacking in 2 causes only a broadening of the band. The magnetic behaviour of 1 and 3 has been investigated by SQUID magnetometry. Both compounds are characterised by a weak antiferromagnetic interaction between the S=1/2 Cr centres of the [(eta6-C6H6)2Cr]+ cations, which is significantly stronger in 1 due to the pi-stacking with the HSQA- anions.
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Affiliation(s)
- D Braga
- Dipartimento di Chimica G. Ciamician, Universita di Bologna, Italy.
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Bürgi HB, Raselli A, Braga D, Grepioni F. Structure of (η6-C6H6)Mo(CO)3 at room temperature and 120 K: motion about equilibrium and far from equilibrium. Acta Crystallogr B Struct Sci 1992. [DOI: 10.1107/s0108768191014404] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Braga D, Grepioni F. Molecular volumes and packing efficiency. An approach to metal cluster properties in the solid state. Acta Crystallogr B Struct Sci 1989. [DOI: 10.1107/s0108768189002922] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Albano VG, Braga D, Grepioni F. Steric and electronic effects on the structural parameters of the dianions [M
6C(CO)15]2– (M = Co, Rh). An accurate analysis. Acta Crystallogr B Struct Sci 1989. [DOI: 10.1107/s0108768188011863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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