Supramolecular architectures in metal(II) (Cd/Zn) halide/nitrate complexes of cytosine/5‐fluorocytosine

Three new metal(II)–cytosine (Cy)/5‐fluorocytosine (5FC) complexes, namely bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)diiodidocadmium(II) or bis(cytosine)diiodidocadmium(II), [CdI₂(C₄H₅N₃O)₂], ( I ), bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)bis(nitrato‐κ²O,O′)cadmium(II) or bis(cytosine)bis(nitrato)cadmium(II), [Cd(NO₃)₂(C₄H₅N₃O)₂], ( II ), and (6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one‐κN³)aquadibromidozinc(II)–6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one (1/1) or (6‐amino‐5‐fluorocytosine)aquadibromidozinc(II)–4‐amino‐5‐fluorocytosine (1/1), [ZnBr₂(C₄H₅FN₃O)(H₂O)]·C₄H₅FN₃O, ( III ), have been synthesized and characterized by single‐crystal X‐ray diffraction. In complex ( I ), the Cd^II ion is coordinated to two iodide ions and the endocyclic N atoms of the two cytosine molecules, leading to a distorted tetrahedral geometry. The structure is isotypic with [CdBr₂(C₄H₅N₃O)₂] [Muthiah et al. (2001). Acta Cryst. E 57 , m558–m560]. In compound ( II ), each of the two cytosine molecules coordinates to the Cd^II ion in a bidentate chelating mode via the endocyclic N atom and the O atom. Each of the two nitrate ions also coordinates in a bidentate chelating mode, forming a bicapped distorted octahedral geometry around cadmium. The typical interligand N—H…O hydrogen bond involving two cytosine molecules is also present. In compound ( III ), one zinc‐coordinated 5FC ligand is cocrystallized with another uncoordinated 5FC molecule. The Zn^II atom coordinates to the N(1) atom (systematic numbering) of 5FC, displacing the proton to the N(3) position. This N(3)—H tautomer of 5FC mimics N(3)‐protonated cytosine in forming a base pair (via three hydrogen bonds) with 5FC in the lattice, generating two fused R₂²(8) motifs. The distorted tetrahedral geometry around zinc is completed by two bromide ions and a water molecule. The coordinated and nonccordinated 5FCs are stacked over one another along the a‐axis direction, forming the rungs of a ladder motif, whereas Zn—Br bonds and N—H…Br hydrogen bonds form the rails of the ladder. The coordinated water molecules bridge the two types of 5FC molecules via O—H…O hydrogen bonds. The cytosine molecules are coordinated directly to the metal ion in each of the complexes and are hydrogen bonded to the bromide, iodide or nitrate ions. In compound ( III ), the uncoordinated 5FC molecule pairs with the coordinated 5FC ligand through three hydrogen bonds. The crystal structures are further stabilized by N—H…O, N—H…N, O—H…O, N—H…I and N—H…Br hydrogen bonds, and stacking interactions.     

Supramolecular architectures in cytosinium 6‐chloronicotinate monohydrate and 5‐bromo‐6‐methylisocytosinium hydrogen sulfate

Aminopyrimidine derivatives are biologically important as they are components of nucleic acids and drugs. The crystals of two new salts, namely cytosinium 6‐chloronicotinate monohydrate, C₄H₆N₃O⁺·C₆H₃ClNO₂⁻·H₂O, ( I ), and 5‐bromo‐6‐methylisocytosinium hydrogen sulfate (or 2‐amino‐5‐bromo‐4‐oxo‐6‐methylpyrimidinium hydrogen sulfate), C₅H₇BrN₃O⁺·HSO₄⁻, ( II ), have been prepared and characterized by single‐crystal X‐ray diffraction. The pyrimidine ring of both compounds is protonated at the imine N atom. In hydrated salt ( I ), the primary R₂²(8) ring motif (supramolecular heterosynthon) is formed via a pair of N—H…O(carboxylate) hydrogen bonds. The cations, anions and water molecule are hydrogen bonded through N—H…O, N—H…N, O—H…O and C—H…O hydrogen bonds, forming R₂²(8), R₃²(7) and R₅⁵(21) motifs, leading to a hydrogen‐bonded supramolecular sheet structure. The supramolecular double sheet structure is formed via water–carboxylate O—H…O hydrogen bonds and π–π interactions between the anions and the cations. In salt ( II ), the hydrogen sulfate ions are linked via O—H…O hydrogen bonds to generate zigzag chains. The aminopyrimidinium cations are embedded between these zigzag chains. Each hydrogen sulfate ion bridges two cations via pairs of N—H…O hydrogen bonds and vice versa, generating two R₂²(8) ring motifs (supramolecular heterosynthon). The cations also interact with one another via halogen–halogen (Br…Br) and halogen–oxygen (Br…O) interactions.     

Design of two series of 1:1 cocrystals involving 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine and carboxylic acids

Two series of a total of ten cocrystals involving 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine with various carboxylic acids have been prepared and characterized by single‐crystal X‐ray diffraction. The pyrimidine unit used for the cocrystals offers two ring N atoms (positions N1 and N3) as proton‐accepting sites. Depending upon the site of protonation, two types of cations are possible [Rajam et al. (2017). Acta Cryst. C 73 , 862–868]. In a parallel arrangement, two series of cocrystals are possible depending upon the hydrogen bonding of the carboxyl group with position N1 or N3. In one series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐bromothiophene‐2‐carboxylic acid (1/1), 1 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐chlorothiophene‐2‐carboxylic acid (1/1), 2 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2,4‐dichlorobenzoic acid (1/1), 3 , and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐aminobenzoic acid (1/1), 4 , the carboxyl hydroxy group (–OH) is hydrogen bonded to position N1 (O—H…N1) of the corresponding pyrimidine unit (single point supramolecular synthon). The inversion‐related stacked pyrimidines are doubly bridged by the carboxyl groups via N—H…O and O—H…N hydrogen bonds to form a large cage‐like tetrameric unit with an R₄²(20) graph‐set ring motif. These tetrameric units are further connected via base pairing through a pair of N—H…N hydrogen bonds, generating R₂²(8) motifs (supramolecular homosynthon). In the other series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐methylthiophene‐2‐carboxylic acid (1/1), 5 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–benzoic acid (1/1), 6 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐methylbenzoic acid (1/1), 7 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐methylbenzoic acid (1/1), 8 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐methylbenzoic acid (1/1), 9 , and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐aminobenzoic acid (1/1), 10 , the carboxyl group interacts with position N3 and the adjacent 4‐amino group of the corresponding pyrimidine ring via O—H…N and N—H…O hydrogen bonds to generate the robust R₂²(8) supramolecular heterosynthon. These heterosynthons are further connected by N—H…N hydrogen‐bond interactions in a linear fashion to form a chain‐like arrangement. In cocrystal 1 , a Br…Br halogen bond is present, in cocrystals 2 and 3 , Cl…Cl halogen bonds are present, and in cocrystals 5 , 6 and 7 , Cl…O halogen bonds are present. In all of the ten cocrystals, π–π stacking interactions are observed.     

Synthesis and characterization of two novel bimetallic macrocyclic complexes generated from 1,2,4‐triazole‐containing semi‐rigid ligands and M(NO3)2 units (M = Ni and Zn)

Bimetallic macrocyclic complexes have attracted the attention of chemists and various organic ligands have been used as molecular building blocks, but supramolecular complexes based on semi‐rigid organic ligands containing 1,2,4‐triazole have remained rare until recently. It is easier to obtain novel topologies by making use of asymmetric semi‐rigid ligands in the self‐assembly process than by making use of rigid ligands. A new semi‐rigid ligand, 3‐[(pyridin‐4‐ylmethyl)sulfanyl]‐5‐(quinolin‐2‐yl)‐4H‐1,2,4‐triazol‐4‐amine (L), has been synthesized and used to generate two novel bimetallic macrocycle complexes, namely bis{μ‐3‐[(pyridin‐4‐ylmethyl)sulfanyl]‐5‐(quinolin‐2‐yl)‐4H‐1,2,4‐triazol‐4‐amine}bis[(methanol‐κO)(nitrato‐κ²O,O′)nickel(II)] dinitrate, [Ni₂(NO₃)₂(C₁₇H₁₄N₆S)₂(CH₃OH)₂](NO₃)₂, (I), and bis{μ‐3‐[(pyridin‐4‐ylmethyl)sulfanyl]‐5‐(quinolin‐2‐yl)‐4H‐1,2,4‐triazol‐4‐amine}bis[(methanol‐κO)(nitrato‐κ²O,O′)zinc(II)] dinitrate, [Zn₂(NO₃)₂(C₁₇H₁₄N₆S)₂(CH₃OH)₂](NO₃)₂, (II), by solution reactions with the inorganic salts M(NO₃)₂ (M = Ni and Zn, respectively) in mixed solvents. In (I), two Ni^II cations with the same coordination environment are linked by L ligands through Ni—N bonds to form a bimetallic ring. Compound (I) is extended into a two‐dimensional network in the crystallographic ac plane via N—H…O, O—H…N and O—H…O hydrogen bonds, and neighbouring two‐dimensional planes are parallel and form a three‐dimensional structure via π–π stacking. Compound (II) contains two bimetallic rings with the same coordination environment of the Zn^II cations. The Zn^II cations are bridged by L ligands through Zn—N bonds to form the bimetallic rings. One type of bimetallic ring constructs a one‐dimensional nanotube via O—H…O and N—H…O hydrogen bonds along the crystallographic a direction, and the other constructs zero‐dimensional molecular cages via O—H…O and N—H…O hydrogen bonds. They are interlinked into a two‐dimensional network in the ac plane through extensive N—H…O hydrogen bonds, and a three‐dimensional supramolecular architecture is formed via π–π interactions between the centroids of the benzene rings of the quinoline ring systems.     

Three new quinuclidine‐based structures: second harmonic generation response for 1,2‐bis(1‐azoniabicyclo[2.2.2]octan‐3‐ylidene)hydrazine dichloride

The crystal structures of three quinuclidine‐based compounds, namely (1‐azabicyclo[2.2.2]octan‐3‐ylidene)hydrazine monohydrate, C₇H₁₃N₃·H₂O ( 1 ), 1,2‐bis(1‐azabicyclo[2.2.2]octan‐3‐ylidene)hydrazine, C₁₄H₂₂N₄ ( 2 ), and 1,2‐bis(1‐azoniabicyclo[2.2.2]octan‐3‐ylidene)hydrazine dichloride, C₁₄H₂₄N₄²⁺·2Cl^? ( 3 ), are reported. In the crystal structure of 1 , the quinuclidine‐substituted hydrazine and water molecules are linked through N—H…O and O—H…N hydrogen bonds, forming a two‐dimensional array. The compound crystallizes in the centrosymmetric space group P2₁/c. Compound 2 was refined in the space group Pccn and exhibits no hydrogen bonding. However, its hydrochloride form 3 crystallizes in the noncentrosymmetric space group Pc. It shows a three‐dimensional network structure via intermolecular hydrogen bonding (N—H…C and N/C—H…Cl). Compound 3 , with its acentric structure, shows strong second harmonic activity.     

Supramolecular interactions in salts/cocrystals involving pyrimidine derivatives of sulfonate/carboxylic acid

The crystal structures of three compounds involving aminopyrimidine derivatives are reported, namely, 5-fluorocytosinium sulfanilate–5-fluorocytosine–4-azaniumylbenzene-1-sulfonate (1/1/1), C₄H₅FN₃O⁺·C₆H₆NO₃S⁻·C₄H₄FN₃O·C₆H₇NO₃S, I , 5-fluorocytosine–indole-3-propionic acid (1/1), C₄H₄FN₃O·C₁₁H₁₁NO₂, II , and 2,4,6-triaminopyrimidinium 3-nitrobenzoate, C₄H₈N₅⁺·C₇H₄NO₄⁻, III , which have been synthesized and characterized by single-crystal X-ray diffraction. In I , there are two 5-fluorocytosine (5FC) molecules (5FC-A and 5FC-B) in the asymmetric unit, with one of the protons disordered between them. 5FC-A and 5FC-B are linked by triple hydrogen bonds, generating two fused rings [two R₂²(8) ring motifs]. The 5FC-A molecules form a self-complementary base pair [R₂²(8) ring motif] via a pair of N—H…O hydrogen bonds and the 5FC-B molecules form a similar complementary base pair [R₂²(8) ring motif]. The combination of these two types of pairing generates a supramolecular ribbon. The 5FC molecules are further hydrogen bonded to the sulfanilate anions and sulfanilic acid molecules via N—H…O hydrogen bonds, generating R₄⁴(22) and R⁶₆(36) ring motifs. In cocrystal II , two types of base pairs (homosynthons) are observed via a pair of N—H…O/N—H…N hydrogen bonds, generating R₂²(8) ring motifs. The first type of base pair is formed by the interaction of an N—H group and the carbonyl O atom of 5FC molecules through a couple of N—H…O hydrogen bonds. Another type of base pair is formed via the amino group and a pyrimidine ring N atom of the 5FC molecules through a pair of N—H…N hydrogen bonds. The base pairs (via N—H…N hydrogen bonds) are further bridged by the carboxyl OH group of indole-3-propionic acid and the O atom of 5FC through O—H…O hydrogen bonds on either side of the R₂²(8) motif. This leads to a DDAA array. In salt III , one of the N atoms of the pyrimidine ring is protonated and interacts with the carboxylate group of the anion through N—H…O hydrogen bonds, leading to the primary ring motif R₂²(8). Furthermore, the 2,4,6-triaminopyrimidinium (TAP) cations form base pairs [R₂²(8) homosynthon] via N—H…N hydrogen bonds. A carboxylate O atom of the 3-nitrobenzoate anion bridges two of the amino groups on either side of the paired TAP cations to form another ring [R₃²(8)]. This leads to the generation of a quadruple DADA array. The crystal structures are further stabilized by π–π stacking ( I and III ), C—H…π ( I and II ), C—F…π ( I ) and C—O…π ( II ) interactions.     

How the oxazole fragment influences the conformation of the tetraoxazocane ring in a cyclohexanespiro‐3′‐(1,2,4,5,7‐tetraoxazocane): single‐crystal X‐ray and theoretical study

Single crystals of (2S,5R)‐2‐isopropyl‐5‐methyl‐7‐(5‐methylisoxazol‐3‐yl)cyclohexanespiro‐3′‐(1,2,4,5,7‐tetraoxazocane), C₁₆H₂₆N₂O₅, have been studied via X‐ray diffraction. The tetraoxazocane ring adopts a boat–chair conformation in the crystalline state, which is due to intramolecular interactions. Conformational analysis of the tetraoxazocane fragment performed at the B3LYP/6‐31G(d,2p) level of theory showed that there are three minima on the potential energy surface, one of which corresponds to the conformation realized in the solid state, but not to a global minimum. Analysis of the geometry and the topological parameters of the electron density at the (3,?1) bond critical points (BCPs), and the charge transfer in the tetraoxazocane ring indicated that there are stereoelectronic effects in the O—C—O and N—C—O fragments. There is a two‐cross hyperconjugation in the N—C—O fragment between the lone electron pair of the N atom (lpN) and the antibonding orbital of a C—O bond (σ*_C—O) and vice versa between lpO and σ*_C—N. The oxazole substituent has a considerable effect on the geometry and the topological parameters of the electron density at the (3,?1) BCPs of the tetraoxazocane ring. The crystal structure is stabilized via intermolecular C—H…N and C—H…O hydrogen bonds, which is unambiguously confirmed with PIXEL calculations, a quantum theory of atoms in molecules (QTAIM) topological analysis of the electron density at the (3,?1) BCPs and a Hirshfeld analysis of the electrostatic potential. The molecules form zigzag chains in the crystal due to intermolecular C—H…N interactions being electrostatic in origin. The molecules are further stacked due to C—H…O hydrogen bonds. The dispersion component in the total stabilization energy of the crystal lattice is 68.09%.     

Hydrogen bonding in the bromide salts of 4‐aminobenzoic acid and 4‐aminoacetophenone

In the title compounds, 4‐carboxyanilinium bromide, C₇H₈NO₂⁺·Br⁻, (I), and 4‐acetylanilinium bromide, C₈H₁₀NO⁺·Br⁻, (II), each asymmetric unit contains a discrete cation with a protonated amino group and a halide anion. Both crystal structures are characterized by two‐dimensional hydrogen‐bonded networks. The ions in (I) are connected via N—H...Br, N—H...O and O—H...Br hydrogen bonds, with three characteristic graph‐set motifs, viz. C(8), C₂¹(4) and R₃²(8). The centrosymmetric hydrogen‐bonded R²₂(8) dimer motif characteristic of carboxylic acids is absent. The ions in (II) are connected via N—H...Br and N—H...O hydrogen bonds, with two characteristic graph‐set motifs, viz. C(8) and R₄²(8). The significance of this study lies in its illustration of the differences between the supramolecular aggregations in two similar compounds. The presence of the methyl group in (II) at the site corresponding to the hydroxyl group in (I) results in a significantly different hydrogen‐bonding arrangement.     

Supramolecular hydrogen‐bonding patterns in the organic–inorganic hybrid compound bis(4‐amino‐5‐chloro‐2,6‐dimethylpyrimidinium) tetrathiocyanatozinc(II)–4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–water (1/2/2)

Zinc thiocyanate complexes have been found to be biologically active compounds. Zinc is also an essential element for the normal function of most organisms and is the main constituent in a number of metalloenzyme proteins. Pyrimidine and aminopyrimidine derivatives are biologically very important as they are components of nucleic acids. Thiocyanate ions can bridge metal ions by employing both their N and S atoms for coordination. They can play an important role in assembling different coordination structures and yield an interesting variety of one‐, two‐ and three‐dimensional polymeric metal–thiocyanate supramolecular frameworks. The structure of a new zinc thiocyanate–aminopyrimidine organic–inorganic compound, (C₆H₉ClN₃)₂[Zn(NCS)₄]·2C₆H₈ClN₃·2H₂O, is reported. The asymmetric unit consist of half a tetrathiocyanatozinc(II) dianion, an uncoordinated 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidinium cation, a 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine molecule and a water molecule. The Zn^II atom adopts a distorted tetrahedral coordination geometry and is coordinated by four N atoms from the thiocyanate anions. The Zn^II atom is located on a special position (twofold axis of symmetry). The pyrimidinium cation and the pyrimidine molecule are not coordinated to the Zn^II atom, but are hydrogen bonded to the uncoordinated water molecules and the metal‐coordinated thiocyanate ligands. The pyrimidine molecules and pyrimidinium cations also form base‐pair‐like structures with an R₂²(8) ring motif via N—H…N hydrogen bonds. The crystal structure is further stabilized by intermolecular N—H…O, O—H…S, N—H…S and O—H…N hydrogen bonds, by intramolecular N—H…Cl and C—H…Cl hydrogen bonds, and also by π–π stacking interactions.     

Crystal structures,thermal stabilities,and dissolution behaviours of tinidazole and the tinidazole–vanillic acid cocrystal: insights from energy frameworks

The crystal structures of the antimicrobial drug tinidazole [ TNZ ; systematic name: 1‐(2‐ethylsulfonylethyl)‐2‐methyl‐5‐nitroimidazole, C₈H₁₃N₃O₄S] and the 1:1 cocrystal of TNZ with the naturally occurring compound vanillic acid ( VA ; systematic name: 4‐hydroxy‐3‐methoxybenzoic acid, C₈H₈O₄), namely, the TNZ – VA cocrystal, were determined by single‐crystal X‐ray analysis at 100 K. The supramolecular structure of the TNZ – VA cocrystal is composed of a carboxylic acid dimer and an O—H…N(heterocycle) synthon in the form of layers made up of O—H…N and O—H…O hydrogen bonds. The layers are joined via C—H…O hydrogen bonds, π–π stacking and C—H…π interactions. The energy framework analysis, together with interaction energy calculations using the DLPNO‐CCSD(T) method, indicates that the TNZ – VA cocrystal inherits strong interactions from the TNZ and VA crystals, which accounts for the enhanced thermal stability and reduced dissolution rate. To the best of our knowledge, this is the first example of a cocrystal containing TNZ .     

Silber(I)‐di(arensulfonyl)amide und ein Silber(I)‐(arensulfonyl)(alkansulfonyl)amid: Von Bändern zu lamellaren Schichten mit kurzen Zwischenschichtkontakten C–H…Hal–C oder C–Br…Br–C

Structures of Ionic Di(arenesulfonyl)amides. 2. Silver(I) Di(arenesulfonyl)amides and a Silver(I) (Arenesulfonyl)(alkanesulfonyl)amide: From Ribbons to Lamellar Layers Exhibiting Short C–H…Hal–C or C–Br…Br–C Interlayer Contacts Low‐temperature X‐ray crystal structures are reported for AgN(SO₂C₆H₄‐4‐X)₂ · H₂O, where X is Cl ( 4 ) or Br ( 5 ), and for AgN(SO₂Ph)(SO₂Me) ( 6 ). Compounds 4 and 5 and the previously described F analogue ( 3 ) are isotypic, though not strictly isostructural (monoclinic, space group P2₁/c, Z = 4, but egregiously large discrepancies of x and z coordinates for corresponding atoms). Throughout this triad, glide‐plane related formula units are linked along the z axis to form infinite ribbons [(ArSO₂)₂N–Ag(μ‐H₂O)]_∞, in which Ag extends its coordination number to five by accepting one Ag–O bond from each of the (ArSO₂)₂N^⊖ ligands in the adjacent units. By means of O–H…O(S) hydrogen bonds, the ribbons are associated into lamellar layers parallel to the xz plane. Owing to the folded conformation of the anions, the layers display an inner polar region of Ag atoms, H₂O molecules and N(SO₂)₂ groups, outer apolar regions of stacked pairs of aryl rings, and interlayer regions hosting the halogen atoms. Inspection of the latter areas provides sound evidence that the distinct juxtapositions of adjacent layers arise from specific interlamellar attractions and repulsions ( 3 : two C–H…F, all F…F beyond the van der Waals limit d_W; 4 : one C–H…Cl, close packing of Cl atoms at Cl…Cl ≈ d_W; 5 : one C–H…Br, one short Br…Br contact < d_W, all other Br…Br > d_W). Structure 6 (monoclinic, P2₁/n, Z = 4) consists of a lamellar coordination polymer, in which the cation accepts one Ag–N and three Ag–O bonds drawn from four different anions. On account of crystal symmetry, the extended ligand has its Ph and Me groups distributed on both sides of the sheet, the phenyl rings forming the apolar regions of the lamella, whereas the smaller methyl groups are integrated into the corrugated inorganic region by means of weak C–H…O hydrogen bonds.     

A novel tetraphenylethylene derivative: 4‐methyl‐N‐[3‐(1,2,2‐triphenylethenyl)phenyl]benzenesulfonamide with aggregation‐induced emission

The novel tetraphenylethylene derivative 4‐methyl‐N‐[3‐(1,2,2‐triphenylethenyl)phenyl]benzenesulfonamide (abbreviated as MTBF), C₃₃H₂₇NO₂S, was synthesized successfully and characterized by single‐crystal X‐ray diffraction, high‐resolution mass spectroscopy and ¹H NMR spectroscopy. MTBF crystallizes in the centrosymmetric monoclinic space group P2₁/c. In the crystal structure, the MTBF molecules are connected into a one‐dimensional band and then a two‐dimensional sheet by hydrogen bonds of the N—H…O and C—H…O types. The sheets are further linked to produce a three‐dimensional network via C—H…π interactions. The molecules aggregate via these intermolecular forces, which restrain the intramolecular motions (RIM) and decrease the energy loss in the aggregation state, so as to open the radiative channels, and thus MTBF exhibits excellent fluorescence by aggregation‐induced emission (AIE) enhancement.     

Exploring concomitant/conformational dimorphism in a difluoro‐substituted phosphoramidate derivative

The concomitant occurrence of dimorphs of diphenyl (3,4‐difluorophenyl)phosphoramidate, C₁₈H₁₄F₂NO₃P, was observed via a solution‐mediated crystallization process with variation in the symmetry‐free molecules (Z′). The existence of two forms, i.e. Form I (block, Z′ = 1) and Form II (needle, Z′ = 2), was characterized by single‐crystal X‐ray diffraction, differential scanning calorimetry and powder X‐ray diffraction. Furthermore, a quantitative analysis of the energetics of the different intermolecular interactions was carried out via the energy decomposition method (PIXEL), which corroborates with inputs from the energy framework and looks at the topology of the various intermolecular interactions present in both forms. The unequivocally distinguished contribution of strong N—H…O hydrogen bonds along with other interactions, such as C—H…O, C—H…F, π–π and C—H…π, mapped on the Hirshfeld surface is depicted by two‐dimensional fingerprint plots. Apart from the major electrostatic contribution from N—H…O hydrogen bonds, the crystal structures are stabilized by contributions from the dispersion energy. The closely related melting points and opposite trends in the calculated lattice energies are interesting to investigate with respect to the thermodynamic stability of the observed dimorphs. The significant variation in the torsion angles in both forms helps in classifying them in the category of conformational polymorphs.     

The synergistic co‐operation of N—H…O=P hydrogen bonds and C—H…OX weak intermolecular interactions (X is =P or —C) in the (CH3O)2P(O)(NH–NHC6F5) amidophosphoester: a combined X‐ray crystallographic and theoretical study

The asymmetric unit of O,O′‐dimethyl [(2,3,4,5,6‐pentafluorophenyl)hydrazinyl]phosphonate, C₈H₈F₅N₂O₃P, is composed of two symmetry‐independent molecules with significant differences in the orientations of the C₆F₅ and OMe groups. In the crystal structure, a one‐dimensional assembly is mediated from classical N—H…O hydrogen bonds, which includes R₂²(8), D(2) and some higher‐order graph‐set motifs. By also considering weak C—H…O=P and C—H…O—C intermolecular interactions, a two‐dimensional network extends along the ab plane. The strengths of the hydrogen bonds were evaluated using quantum chemical calculations with the GAUSSIAN09 software package at the B3LYP/6‐311G(d,p) level of theory. The LP(O) to σ*(NH) and σ*(CH) charge‐transfer interactions were examined according to second‐order perturbation theory in natural bond orbital (NBO) methodology. The hydrogen‐bonded clusters of molecules, including N—H…O and C—H…O interactions, were constructed as input files for the calculations and the strengths of the hydrogen bonds are as follows: N—H…O [R₂²(8)] > N—H…O [D(2)] > C—H…O. The decomposed fingerprint plots show that the contribution portions of the F…H/H…F contacts in both molecules are the largest.     

Weak hydrogen bonding and fluorous interactions in the chloride and bromide salts of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium

Neutralization of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium chloride, C₉H₁₀F₄NO⁺·Cl⁻, (1), and 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium bromide, C₉H₁₀F₄NO⁺·Br⁻, (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single‐crystal X‐ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N—H, ortho‐C—H and CF₂—H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N—H…X …H—Csp ³ connections. These dimers are further crosslinked, utilizing another complimentary Csp ²—H…X …H—Csp ² connection. The pyridinium rings are π‐stacked, forming columns running parallel to the a axis that make angles of ca 44–45° with the normal to the pyridinium plane. There are also supramolecular C—H…F—C interactions, namely bifurcated C—H…F and bifurcated C—F…H interactions; additionally, one type II C—F…F—C halogen bond has been observed.     

Complexes of nickel(II) and copper(II) with 1,2,4‐triazole‐3‐carboxylic acid and of cobalt(III) with 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid

Because of their versatile coordination modes and strong coordination ability for metals, triazole ligands can provide a wide range of possibilities for the construction of metal–organic frameworks. Three transition‐metal complexes, namely bis(μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato)‐κ³N ²,O :N ¹;κ³N ¹:N ²,O‐bis[triamminenickel(II)] tetrahydrate, [Ni₂(C₃HN₃O₂)₂(NH₃)₆]·4H₂O, (I), catena‐poly[[[diamminediaquacopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ¹:N ⁴,O‐[diamminecopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ⁴,O :N ¹] dihydrate], {[Cu₂(C₃HN₃O₂)₂(NH₃)₄(H₂O)₂]·2H₂O}_n , (II), (μ‐5‐amino‐1,2,4‐triazol‐1‐ide‐3‐carboxylato‐κ²N ¹:N ²)di‐μ‐hydroxido‐κ⁴O :O‐bis[triamminecobalt(III)] nitrate hydroxide trihydrate, [Co₂(C₃H₂N₄O₂)(OH)₂(NH₃)₆](NO₃)(OH)·3H₂O, (III), with different structural forms have been prepared by the reaction of transition metal salts, i.e. NiCl₂, CuCl₂ and Co(NO₃)₂, with 1,2,4‐triazole‐3‐carboxylic acid or 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid hemihydrate in aqueous ammonia at room temperature. Compound (I) is a dinuclear complex. Extensive O—H…O, O—H…N and N—H…O hydrogen bonds and π–π stacking interactions between the centroids of the triazole rings contribute to the formation of the three‐dimensional supramolecular structure. Compound (II) exhibits a one‐dimensional chain structure, with O—H…O hydrogen bonds and weak O—H…N, N—H…O and C—H…O hydrogen bonds linking anions and lattice water molecules into the three‐dimensional supramolecular structure. Compared with compound (I), compound (III) is a structurally different dinuclear complex. Extensive N—H…O, N—H…N, O—H…N and O—H…O hydrogen bonding occurs in the structure, leading to the formation of the three‐dimensional supramolecular structure.     

Hydrogen‐bonded supramolecular polymers containing dimethylsilane groups: Synthesis,crystal structure,and characterization

Bis[N‐(4‐carboxyphenyl)phtalimidyl]dimethylsilane prepared by the reaction between bis(3,4‐dicarboxyphenyl)dimethylsilane anhydride and p‐aminobenzoic acid has been used to built three novel hydrogen‐bonded supramolecular polymers as a result of cocrystallization with pyridine derivatives: 4,4′‐bipyridyl ( SP1 ), 1,2‐bis(4‐pyridyl)ethylene ( SP2 ), and 4,4′‐azopyridine ( SP3 ). The structures of the dianhydride, diacid, and derived supramolecular polymers were investigated by Fourier transform infrared (FTIR) and proton magnetic resonance (¹H NMR) spectroscopy. Self‐assembling was proved by the presence of the IR absorption bands around 1900 and 2400 cm^?1 specific for hydrogen bond. The association constant values were estimated by using FTIR spectroscopy in solid state. According to X‐ray diffraction study, the bis(3,4‐dicarboxyphenyl)dimethylsilane anhydride ( 1 ) has an isolated molecular structure. Bis[N‐(4‐carboxyphenyl)phtalimidyl]dimethylsilane ( 2 ) molecules are associated in the crystal structure via dimeric O? H … O hydrogen bonds resulting in the wavy 1D supramolecular chain. The main packing motif for SP1 and SP3 is represented by wavy chain formed by alternating sequences of 4,4′‐bipyridyl or 4,4′‐azopyridine and bis[N(4‐carboxyphenyl)phtalimidyl]dimethylsilane molecules linked by O? H … N hydrogen bonds. Thermal behavior was studied by differential scanning calorimetry and thermogravimetric analysis. The ability for the structuration in film was emphasized by atomic force microscopy. The molecular transport ability of the reversible associations was estimated by dynamic water vapor sorption (DVS) analysis. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Different supramolecular interactions mediated by Br atoms in the crystal structures of three anisole derivatives

Three anisole building blocks featuring bis(hydroxymethyl) or bis(bromomethyl) pendants have been analyzed with regard to their molecular structures and packing behaviour. The compounds are ethyl 3,5‐bis(hydroxymethyl)‐4‐methoxybenzoate, C₁₂H₁₆O₅, (I), [5‐bromo‐3‐(hydroxymethyl)‐2‐methoxyphenyl]methanol [or 4‐bromo‐2,6‐bis(hydroxymethyl)anisole], C₉H₁₁BrO₃, (II), and 5‐bromo‐1,3‐bis(bromomethyl)‐2‐methoxybenzene [or 4‐bromo‐2,6‐bis(bromomethyl)anisole], C₉H₉Br₃O, (III). A typical supramolecular pattern involved C—H…π interactions generating molecular stacks, while π–π interactions were only observed in the absence of bromine, indicating a striking influence on the distances between adjacent aromatic moieties. When comparing bis(hydroxymethyl) compound (II) with bis(bromomethyl) compound (III), we found that the strong O—H…O hydrogen bonds in a zigzag arrangement in the first are replaced by C—H…Br interactions in the second without a change in the general packing.     

The role of different nonspecific interactions and halogen contacts in the crystal structure organization of 5‐chloroisatoic anhydride

The crystal structure of 6‐chloro‐2,4‐dihydro‐1H‐3,1‐benzoxazine‐2,4‐dione (5‐chloroisatoic anhydride), C₈H₄ClNO₃, has been determined and analysed in terms of connectivity and packing patterns. The compound crystallizes in the noncentrosymmetric space group Pna2₁ with one molecule in the asymmetric unit. The role of different weak interactions is discussed with respect to three‐dimensional network organization. Molecules are extended into one‐dimensional helical arrangements, making use of N—H…O hydrogen bonds and π–π interactions. The helices are further organized into monolayers via weak C—H…O and lone pair–π interactions, and the monolayers are packed into a noncentrosymmetric three‐dimensional architecture by C—Cl…π interactions and C—H…Cl and Cl…Cl contacts. A Hirshfeld surface (HS) analysis was carried out and two‐dimensional (2D) fingerprint plots were generated to visualize the intermolecular interactions and to provide quantitative data for their relative contributions. In addition, tests of the antimicrobial activity and in vitro cytotoxity effects against fitoblast L929 were performed and are discussed.     

Mechanochemical synthesis and X‐ray structural characterization of three 3‐nitrophenol cocrystals with three aminal cage azaadamantanes: the role of the stereoelectronic effect on intermolecular hydrogen‐bonding patterns

The structures of the cocrystalline adducts of 3‐nitrophenol (3‐NP) with 1,3,5,7‐tetraazatricyclo[3.3.1.1^3,7]decane [HMTA, ( 1 )] as the 2:1:1 hydrate, 2C₆H₅NO₃·C₆H₁₂N₄·H₂O, ( 1a ), with 1,3,6,8‐tetraazatricyclo[4.3.1.1^3,8]undecane [TATU ( 2 )] as the 2:1 cocrystal, 2C₆H₅NO₃·C₇H₁₄N₄, ( 2a ), and with 1,3,6,8‐tetraazatricyclo[4.4.1.1^3,8]dodecane [TATD, ( 3 )] as the 2:1 cocrystal, 2C₆H₅NO₃·C₈H₁₆N₄, ( 3a ), are reported. In the binary crystals ( 2a ) and ( 3a ), the 3‐nitrophenol molecules are linked via O—H…N hydrogen bonds into aminal cage azaadamantanes. In ( 1a ), the structure is stabilized by O—H…N and O—H…O hydrogen bonds, and generates ternary cocrystals. There are C—H…O hydrogen bonds present in all three cocrystals, and in ( 1a ), there are also C—H…O and C—H…π interactions present. The presence of an ethylene bridge in the structures of ( 2 ) and ( 3 ) defines the formation of a hydrogen‐bonded motif in the supramolecular architectures of ( 2a ) and ( 3a ). The differences in the C—N bond lengths of the aminal cage structures, as a result of hyperconjugative interactions and electron delocalization, were analysed. These three cocrystals were obtained by the solvent‐free assisted grinding method. Crystals suitable for single‐crystal X‐ray diffraction were grown by slow evaporation from a mixture of hexanes.