Discriminating octahedral transition metal ions: highly selective tripodal tris-(2,2′-bipyridine) functionalized piperazine cyclophane receptor for Cu2+ ions

New tripodal transition metal ion receptors, tris(5-ethoxycarbonyl-2,2'-bipyridine) and tris(5-carboxylate-2,2'-bipyridine) substituted 27-membered trimeric piperazine cyclophanes 5 and 7 as well as tetra(5-ethoxycarbonyl-2,2'-bipyridine) substituted 36-membered tetrameric piperazine cyclophane 6, have been prepared and their transition metal ion complexing properties studied in solution by UV-vis spectroscopy and in the solid state by single-crystal X-ray diffraction. The crystal structures of [H(3)5(3+)·Fe(2+)]·4(ClO(4)(-))·CF(3)COO(-) (V), [H(3)7(2+)·Fe(2+)]·2(SO(4)(2-)) (VII) and the reference complex [tris(5,5'-bis(ethoxycarbonyl)-2,2'-bipyridine)Fe(II) perchlorate] (I) showed that the…

In the Pursuit of Efficient Anion-Binding Organic Ligands Based on Halogen Bonding

The syntheses and the crystal structures of new multitopic anion-binding organic ligands based on a benzenoid scaffold and bearing two or three 2-iodo-imidazolium arms are reported. The quite short...

Alternative Motifs for Halogen Bonding

The halogen-bonding interaction is one of the rising stars in supramolecular chemistry. Although other weak interactions and their influence on the structure and chemistry of various molecules, complexes and materials have been investigated thoroughly, the field of halogen bonding is still quite unexplored and its impact on chemistry in general is yet to be fully revealed. In principle, every Y–X bond (Y = electron-withdrawing atom or moiety, X = halogen atom) can act as a halogen-bond donor when the halogen is polarized enough by Y. Perfluorohalocarbons are iconic halogen-bond donor molecules in which Y is a perfluorinated aryl or alkyl moiety and X is either iodine or bromine. In this art…

Hierarchical halogen bonding induces polymorphism

Co-crystals of 1-iodo-3,5-dinitrobenzene and 1,4-diazabicyclo[2.2.2]octane manifest either two strong or one strong and one weak intermolecular 2 : 1 halogen bond (XB) motifs in polymorphic structures I and II, respectively, whereas weaker XB-donor 4,4-bipyridine just forms 1 : 1 structure III with one strong halogen bond.

Molecular Pacman: Folding, Inclusion, and X-ray Structures of Tri- and Tetraamino Piperazine Cyclophanes

Reaction of piperazine and 1,3-bis(bromomethyl)-2-nitrobenzene under high-dilution conditions yields cyclic trimeric trinitro, tetrameric tetranitro, and pentameric pentanitro piperazine cyclophanes. Reduction of the nitro groups with SnCl(2) under acidic conditions produces the corresponding triamino and tetraamino piperazine cyclophanes. The solution studies of both nitro and amino piperazine cyclophanes at 30 degrees C by (1)H NMR spectroscopy shows symmetrical structures owing to the fast conformational exchange, whereas the low temperature studies of the tetraamino piperazine cyclophane reveals interesting dynamic behavior that indicates additional intramolecular interactions. Careful …

Interaction Between Amines and N-Haloimides: a New Motif for Unprecedentedly Short Br...N and I...N Halogen Bonds

The complexes of N-bromosuccinimide or N-iodosuccinimide with a halogen bond acceptor, either 1,4-diazabicyclo[2.2.2]octane (DABCO), hexamethylenetetramine (HMTA) or 1,3,5-triazine (TRZ), led to an unprecedentedly strong (CO)2N–X⋯N halogen bond synthon (X = Br or I) determined from crystal structures of [DABCO]·[NBS]22, [HMTA]·[NBS]22, [TRZ]·[NIS]22 and [HMTA]·[NIS]44. The Br⋯N distances with DABCO and with HMTA donors were 2.347 A and 2.414 A being remarkably shorter (31% and 29%) than the sum of the VDW radii of nitrogen and bromide atoms, respectively. The corresponding I⋯N distances with HMTA and TRZ were 2.549 A and 2.596 A (27.8% and 26.4% less than the sum of the VDW radii of N and I…

Halogen bonding drives the self-assembly of piperazine cyclophanes into tubular structures.

Halogen bonding with 1,4-diiodotetrafluorobenzene leads to the self-assembly of piperazine cyclophanes into well-defined tubular structures with solvent inclusion.

(Dimethylformamide)dioxobis(pentane-2,4-dionato)uranium(VI)

The title complex, [UO2(C5H7O2)2(C3H7NO)], was obtained as an unexpected product from our attempts to prepare UIV complexes with imine-type ligands. The title complex was also prepared directly from [UO2(OAc)2]·2H2O, pentane-2,4-dione and DMF. The UVI atom has a penta­gonal-bipyramidal geometry and is surrounded by seven O atoms. The bond distances and angles are similar to those found previously in similar structures.

Alternative Motifs for Halogen Bonding (Eur. J. Org. Chem. 9/2013)

Breathing molecular crystals: halogen- and hydrogen-bonded porous molecular crystals with solvent induced adaptation of the nanosized channels

Exceptionally strong (OC–)2N–I⋯N halogen bonding (XB) in a combination with CO⋯H–C hydrogen bonds (HB) between N-iodosuccinimide (NIS) and hexamethylenetetramine (HMTA) yielded a series of molecular crystals possessing large 1D channels. In each structure, HMTA was tetra-coordinated by four NIS molecules resulting in robust [HMTA]·[NIS]4 complexes where the observed I⋯N distances, ranging from 2.486 to 2.586 A, were remarkable shorter (from 29.6 to 26.7%) than the sum of the vdW radii of nitrogen and iodine atoms. Multiple CO⋯H–C HBs interconnected the [HMTA]·[NIS]4 complexes into the structures with flexible “breathing” host-channels. Three different host-channel structures, either oval or…

Modulation of N···I and +N−H···Cl−···I Halogen Bonding: Folding, Inclusion, and Self-Assembly of Tri- and Tetraamino Piperazine Cyclophanes

The acidity of the crystallization conditions was successfully employed in modulating the balance between the robust intramolecular hydrogen bonding (HB) and intermolecular halogen bonding (XB) observed in large tri- (1) and tetraamino (2) piperazine cyclophanes. A careful crystallization of the title XB acceptor cyclophanes with a strong bidentate XB donor 1,4-diiodotetrafluorobenzene (F4DIB) from CHCl3:MeOH, dimethylformamide (DMF), or HCl:H2O:EtOH resulted in X-ray quality crystals of 1·F4DIB, 2@DMF, 2·2@F4DIB, [1H3]Cl3·(F4DIB)6, and [2H6]Cl6·(F4DIB)2. The intramolecular hydrogen bonding pattern in 1 and 2 was retained in neutral protic and aprotic solvents, and regular N−H···N hydrogen …

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

The series of haloanilinium and halopyridinium salts: 4-IPhNH3Cl (1), 4-IPhNH3Br (5), 4-IPhNH3H2PO4 (6), 4-ClPhNH3H2PO4 (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Bas…

Tri- and tetraurea piperazine cyclophanes: synthesis and complexation studies of preorganized and folded receptor molecules.

A series of symmetrical tri- and tetrameric N-ethyl- and N-phenylurea-functionalized cyclophanes have been prepared in nearly quantitative yields (86-99 %) from the corresponding tri- and tetraamino-functionalized piperazine cyclophanes and ethyl or phenyl isocyanates. Their conformational and complexation properties have been studied by single-crystal X-ray diffraction, variable-temperature NMR spectroscopy, and ESI-MS analysis. The rigid 27-membered trimeric cyclophane skeleton assisted by a seam of intramolecular hydrogen bonds results in a preorganized ditopic recognition site with an all-syn conformation of the urea moieties that, complemented by a lipophilic cavity of the cyclophane, …

CCDC 782860: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782859: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782858: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782862: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782861: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782863: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

CCDC 782856: Experimental Crystal Structure Determination

Related Article: Kari Raatikainen, Massimo Cametti, Kari Rissanen|2010|Beilstein J.Org.Chem.|6|4|doi:10.3762/bjoc.6.4

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

The series of haloanilinium and halopyridinium salts: 4-IPhNH₃Cl (1), 4-IPhNH₃Br (5), 4-IPhNH₃H₂PO₄ (6), 4-ClPhNH₃H₂PO₄ (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Bas…