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Synthetic multimetallic porphyrinoids are potential candidates in catalysis, molecular magnetism and as modern optoelectronic materials. Introducing electronic heterogenity in these multi‐porphyrinoids shall bring in novel electronic and redox characteristics. In this direction, herein we report four discrete Corrole‐Porphyrin‐Corrole C[10] ⋅ P[5,15] ⋅ C[10] hybrids that have both corrole and porphyrin units covalently connected together. Metal ions in diverse oxidation states have been incorporated into respective cores to achieve homo and heterotrinuclear metal complexes. Selective metalation at the porphyrin and corrole cores was achieved by step‐wise insertion of Zn(II)/Cu(II), Zn(II)/Ga(III) and Cu(II)/Cu(II) ions to suit the dianionic and trianionic pockets, respectively. Single crystal X‐ray diffraction studies reveal the solid‐state structural evidence for both homo‐, and hetero‐trinuclear metal complexes. The Zn(II) and Ga(III) moieties have two distinct geometries in the molecular assembly. The geometry of Zn(II) at the porphyrin core is a perfect square planar, whereas the Ga(III) geometry at the corrole is square pyramidal with pyridine as an axial ligand. In case of homotrinuclear Cu(II) complex, the Cu(II) ions adopt square planar geometry irrespective of the core. Similar to all porphyrin trimers, C[10] ⋅ P[5,15] ⋅ C[10] trimers exhibit significant excitonic coupling between corrole and porphyrin units in the absorption spectra. The cyclic voltametric investigations also reveal electronic coupling between the individual chromophores despite the non‐coplanar arrangement amongst the individual macrocycles. [ABSTRACT FROM AUTHOR]

We report a rare incidence of crystal dimorphism in the case of molecule N1,N2-bis(3-(trifluoromethyl)phenyl)oxalamide which exhibits a variable fractional number of symmetry free molecules (Z′) in the structures. The extensive solution mediated and melt crystallization results in form I (Z′ = 1/2, half molecule) and form II (Z′ = 1/2 + 1/2, two half molecules) polymorphic forms, respectively, and exclusively. A quantitative structural description with the energetics of intermolecular interactions for both polymorphs has been demonstrated thoroughly. The existence of two different molecular conformations and better energetic stabilization of the interaction topology rationalizes the high Z′ structure selection by the molecule in the case of form II. [ABSTRACT FROM AUTHOR]

The role of different intermolecular interactions in the crystal structures of halogen‐substituted indoles which are fused with six‐membered or seven‐membered cyclic rings is investigated here. Several crystal structures show isostructural characteristics due to the presence of similar supramolecular motifs. In the absence of any strong hydrogen bonds, the molecular packing of reported structures is primarily stabilized by the presence of non‐classical N—H…π and C—H…π interactions in addition to C—H…X (X = F/Cl/Br) interactions. The nature and energetics of primary and secondary dimeric motifs are partitioned into the electrostatics, polarization, dispersion and exchange–repulsion components using the PIXEL method. Short and directional N—H…π interactions are further explored by a topological analysis of the electron density based on quantum theory of atoms in molecules. [ABSTRACT FROM AUTHOR]

Crystallization of an organic compound, namely, resorcinol, has been studied in a thermal gradient over a substrate where samples are, in addition, mechanically displaced at a constant rate. In such an experiment, nucleation and growth occur in well-defined dissipative conditions. The results show the capability of this method to produce thin films in the resorcinol ß-form. Further, the alignment of the crystals within these films is along a preferred orientation. Employing polarized optical microscopy and X-ray diffraction measurements in terms of specular diffraction and pole figures shows that the crystals alignment follows the thermal gradient. Variation of the displacement rate, i.e., the sample velocity in the gradient field, shows additionally strong variation of the crystal orientations, showing that the kinetic of the crystal formation is crucial for the alignment in the thermal gradient. [ABSTRACT FROM AUTHOR]

Thiophene-containing molecular materials are recognised as efficient substrates in organic photovoltaics. Herein, we have demonstrated the effect of substitution patterns of thiophenes on the electron accepting ability of perylene bisimide derivatives, which in turn dictates the photovoltaic performance. The thiophene units were integrated through α- or β-positions on the 1- or 1,7-bay positions of perylene-bisimide through alkyne spacers in order to modulate the electronic properties of PBI. The target molecules are structurally robust as per electrochemical studies and exhibited broad absorption in the visible region. Better light harvesting ability and favourable LUMO energy levels render these dyads and triads suitable as electron acceptors in organic solar cells. Bulk heterojunction solar cells were constructed from thienyl–PBI (1–4) as acceptors and a polymer P as a donor. α-Linked 1 and 3 showed a PCE of 5.72% and 6.94% with a remarkable energy loss of 0.55 eV and 0.58 eV, respectively whereas, β-linked 2 and 4 showed an overall PCE of 4.93% and 6.06% with an energy loss of 0.52 eV and 0.54 eV, respectively. [ABSTRACT FROM AUTHOR]

Solution-processed bulk-heterojunction organic solar cells have been achieved using unsymmetrical metalloporphyrin–PBI dyads as small molecular donors. Due to panchromatic absorption, a photon-to-current conversion efficiency of 6.18% was obtained for 3-Zn:PC71BM with a remarkable energy loss (Eloss) of 0.60 eV, which is in line with the best values recorded so far for porphyrin-based small-molecular donors. [ABSTRACT FROM AUTHOR]

A detailed experimental (SCXRD) and theoretical (PIXEL and QTAIM) investigation of the evolution of different supramolecular motifs formed via the presence of both C(sp2)/(sp3)–F groups in the crystal packing has been performed in a series of newly synthesized substituted benzanilides (containing “both” the fluorine and the trifluoromethyl group in the same molecule) along with previously reported similarly related crystal structures [CrystEngComm, 2008, 10, 54–67; CrystEngComm, 2012, 14, 1972–1989, CrystEngComm, 2013, 15, 3711–3733]. It was observed that the highest stabilized molecular motifs primarily consist of C(sp2)–H…F–C(sp2) H-bonds in preference to C(sp2)–H…F–C(sp3) H-bonds in the crystal. The motifs involving C(sp2)–H…F–C(sp2)/(sp3) H bonds were observed to be present over the entire distance range between 2.2 and 2.7 Å, albeit the difference in energies of stabilization involving fluorine atoms attached to sp2 and sp3 carbon is not significant in molecular crystals. From QTAIM analysis, the C(sp2)/(sp3)–F…F–C(sp2)/(sp3) interactions were observed to be a closed shell in nature and provide local stabilization, indicating the formation of bonds, similar to weak hydrogen bonds observed in crystals. [ABSTRACT FROM AUTHOR]

The occurrence of concomitant dimorphism has been observed in the case of trifluoromethyl substituted benzanilide, namely, 3-(trifluoromethyl)-N-[2-(trifluoromethyl)phenyl]benzamide, wherein both forms show the presence of a multiple number of molecules in the asymmetric unit (Z′ > 1). Thermal studies confirm the "extremely rare occurrence" of simultaneous melting and solid-to-solid phase transition at the same temperature from centrosymmetric, Z′ = 2 structure (triclinic, P1̅, form I) to noncentrosymmetric, Z′ = 4 structure (monoclinic, Cc). Both forms exhibit similar density and lattice energy. Conformationally different molecules in the asymmetric unit in both the high-Z′ structures are observed to be connected with strong N-H···OC and weak C-H···OC hydrogen bonds. The dissimilarities in the crystal packing were analyzed by Xpac method, and the molecule-molecule interaction energies were evaluated by the PIXEL method. The results revealed the presence of 2D isostructurality between the two forms which mainly consists of the most stabilized intermolecular interactions (namely, strong N- H···OC, C-H···OC, and C-H···π hydrogen bonds) in their crystal packing while differences in their crystal packing are mainly on account of the presence of weak C-H···F-C(sp³) hydrogen bond and C(sp³)-F···F-C(sp³) interactions. [ABSTRACT FROM AUTHOR]

A detailed analysis of the molecular and crystal packing of a series of pharmaceutically active triazolothiadiazole derivatives is reported. The most notable feature from the analysis of the supramolecular motifs is the presence of inversion dimers due to the formation of strong S···N chalcogen bonds. This has been unequivocally established via inputs from energy calculations from PIXEL, the topological analysis using the approach of QTAIM from AIMALL, an analysis of the molecular electrostatic potentials plotted on Hirshfeld surfaces, and the analysis of the 3D-deformation densities obtained using Crystal Explorer. The total interaction energy for this contact is in the range of 28-33 kJ/mol in the molecules under investigation, and the electrostatic (Coulombic + polarization) contribution toward the total stabilization energy is more than 70%, indicating that such interactions are principally electrostatic in origin. The results from the analysis of the molecular ESP depict that this interaction exists between a strongly electropositive σ-hole on the sulfur atom and an electronegative region on the nitrogen. 3D-deformation density (DD) maps reveal the presence of a charge depletion (CD) region on the sulfur atom which is directed toward the charge concentration (CC) region on the nitrogen atom facilitating formation of such contacts in the crystal. These are further invesigated by QTAIM based calculations which establish the closed-shell nature of these contacts. The crystal packing is further stabilized by the presence of significantly important π···π stacking interactions, wherein the interaction energies, calculated by the PIXEL method, reveal that some of these interactions in crystals have significant contributions from electrostatic components, with a lesser contribution from dispersion forces that normally dominate such interactions. The existence of a contribution of ∼48% from electrostatics between stacked rings owing to their unique electrostatic complementarity is a rare supramolecular feature observed in crystal packing in these solids. In addition, the existence of C-H···O, C-H···N, C-H···F, and Cl···N interactions is also characterized by a significant electrostatic component in their formation in crystals of these compounds. [ABSTRACT FROM AUTHOR]

The knowledge about the prevalence of weak interactions in terms of the nature and energetics associated with their formation is of significance in organic solids. In the present study, we have systematically explored the existence of different types of intermolecular interactions in ten out of the fifteen newly synthesized trifluoromethyl derivatives of isomeric N-methyl-N-phenylbenzamides. Detailed analyses of all the crystalline solids were performed with quantitative inputs from interaction energy calculations using the PIXEL method. These studies revealed that in the absence of a strong hydrogen bond, the crystal packing is mainly stabilized by a cooperative interplay of weak C–H…O=C, C–H…π, and C(sp2)/(sp3)–H…F–C(sp3) hydrogen bonds along with other related interactions, namely, π…π and C(sp3)–F…F–C(sp3). It is of interest to observe the presence of short and directional weak C–H…O=C hydrogen bonds in the packing, having a substantial electrostatic (coulombic + polarization) contribution towards the total stabilization energy. The C(sp3)–F group was recognized in the formation of different molecular motifs in the crystal packing as utilizing different intermolecular interactions. The contribution from electrostatics among the different weak hydrogen bonds was observed in the decreasing order: C–H…O=C ＞ C–H…F–C(sp3) ＞ C–H…π. Furthermore, there was an increase in the electrostatic component with a concomitant decrease in the dispersion component for the shorter and directional hydrogen bonds. [ABSTRACT FROM AUTHOR]

A new polymorph belonging to the tetrahydropyrimidinium class of compounds, namely 6-(4-chlorophenyl)-5-(methoxycarbonyl)-4-methyl-2-(3-(trifluoromethylthio)phenylamino)-3,6-dihydropyrimidin-1-ium chloride, and a hydrate of 2-(3-bromophenylamino)-6-(4-chlorophenyl)-5-(methoxycarbonyl)-4-methyl-3,6-dihydropyrimidin-1-ium chloride, have been isolated and characterized using single-crystal X-ray diffraction (XRD). A detailed comprehensive analysis of the crystal packing in terms of the associated intermolecular interactions and a quantification of their interaction energies have been performed for both forms of the two different organic salts ( A and B) using X-ray crystallography and computational methods such as density functional theory (DFT) quantum mechanical calculations, PIXEL lattice-energy calculations (with decomposition of total lattice energy into the Coulombic, polarization, dispersion and repulsion contribution), the calculation of the Madelung constant (the EUGEN method), Hirshfeld and two-dimensional fingerprint plots. The presence of ionic [N-H]+...Cl− and [C-H]+...Cl− hydrogen bonds mainly stabilizes the crystal packing in both forms A and B, while in the case of B·H2O [N-H]+...Owater and Owater-H...Cl− hydrogen bonds along with [N-H]+...Cl− and [C-H]+...Cl− provide stability to the crystal packing. The lattice-energy calculations from both PIXEL and EUGEN methods revealed that in the case of A, form (I) (monoclinic) is more stable whereas for B it is the anhydrous form that is more stable. The analysis of the `Madelung mode' of crystal packing of two forms of A and B and its hydrates suggest that differences exist in the position of the charged ions/atoms in the organic solid state. The R/ E (distance-energy) plots for all the crystal structures show that the molecular pairs in their crystal packing are connected with either highly stabilizing (due to the presence of organic R+ and Cl −) or highly destabilizing Coulombic contacts. The difference in crystal packing and associated intermolecular interactions between polymorphs (in the case of A) or the hydrates (in the case of B) have been clearly elucidated by the analysis of Hirshfeld surfaces and two-dimensional fingerprint plots. The relative contributions of the various interactions to the Hirshfeld surface for the cationic (dihydropyrimidinium) part and anionic (chloride ion) part for the two forms of A and B and its hydrate were observed to be different. [ABSTRACT FROM AUTHOR]

Thefirst example of an azepine ring formation by counterintuitive nucleophilicparticipation of DBU was observed at the sterically crowded bay areaof electron-deficient perylenebisimide (PBI). This is also a rareexample of the formation of a seven-membered ring via two consecutiveC–N bond formations in a single step. Azepino-PBIs reveal panchromaticabsorption covering the whole visible region. Further novelty of thesePBIs lies within the fact that their photophysical characteristicscan easily be modulated by suitable substituents. [ABSTRACT FROM AUTHOR]

Theexistence of short H-bonds with organic fluorine is still underdebate. We report herein the occurrence and nature of such short contactsto fluorine connected to an aromatic ring in the block form of N-(4-fluorophenyl)-3-(trifluoromethyl) benzamide and 4-fluoro-N-[3-(trifluoromethyl)phenyl]benzamide. The magnitude ofthe stabilizing interaction energy is −2.15 and −2.89kcal/mol, respectively. It is important to note that such contactshave been observed in the presence of strong NH···OCH-bonds whose energies are in the range of 6.0–8.0 kcal/mol.Thus, the observed strength of an H-bond with fluorine is ∼30–40%of the strength of a strong traditional H-bond in amides. The acidichydrogens were observed to be involved in the formation of a shortCH···F contact, the interaction energy havinga substantial Coulombic contribution in comparison to the other weakinteractions which are primarily of a dispersive character as obtainedby PIXEL method. A full topological analysis does establish the factthat CH···F interactions at short distancesare indeed a “true H-bond”. These are not a consequenceof crystal packing and have implications in the generation of polymorphsin the solid state. This is expected to have implications in the bindingof a ligand (organic molecule containing fluorine) with the proteinactive site. [ABSTRACT FROM AUTHOR]

Perylene bisimide (PBI) derivatives with various alkynyl-phenyl substituents at a single bay position have been synthesised by Sonogashira coupling. NMR spectroscopic studies reveal the unsymmetric nature of the dyads. All of the dyads undergo two reversible reductions, which demonstrates their structural and electrochemical rigidity. The synthesised dyads show a remarkable redshift in their absorption maxima and sharp vibronic progression. Electron-rich substituents facilitate efficient charge transfer from the substituent HOMO to the electron-deficient PBI core. The most interesting spectral signatures were exhibited by a PBI with a strongly electron-donating ethynyl(dimethylaminophenyl) substituent. The steady-state features of this PBI showed a broad absorption that covered almost the whole visible region with no emission. A twisted intramolecular charge-transfer (TICT) process, related to the rotational motion of ethynyl(dimethylaminophenyl) PBI, was also demonstrated. Computational investigations shed light on the coplanarity of the various substituents with respect to the PBI core; the PBI core itself remains flat without any noticeable deformation even after mono-functionalisation. This illustrates that mono-functionalisation exerts meagre steric hindrance on the bay positions relative to disubstituted analogues. Despite several previous reports on the structural characterisation of 1,7-disubstituted PBI derivatives, we present the first structural characterisation of a mono-bay ethynyl-phenyl substituted PBI. The solid-state structure of the phenyl derivative has a flat PBI core without any noticeable steric constraints from the substituents, as predicted. In contrast, single-crystal X-ray analysis for the mono-bromo bay-substituted PBI shows that the bromine substituent is not in the plane of the PBI core. [ABSTRACT FROM AUTHOR]

The aim of this paper was to investigate whether a surface coating technique could be developed that can predict the phase behavior of amorphous solid dispersions (ASDs) coated on beads. ASDs of miconazole (MIC) and poly(vinylpyrrolidone-co-vinyl acetate) (PVP-VA) in methanol (MeOH) were studied as a model system. First, the low crystallization tendency of the model drug in MeOH was evaluated and confirmed. In a next step, a drug loading screening was performed on casted films and coated beads in order to define the highest possible MIC loading that still results in a one-phase amorphous system. These results indicate that film casting is not suitable for phase behavior predictions of ASDs coated on beads. Therefore, a setup for coating a solid surface was established inside the drying chamber of a spray dryer and it was found that this surface coating technique could predict the phase behavior of MIC-PVP-VA systems coated on beads, in case an intermittent spraying procedure is applied. Finally, spray drying was also evaluated for its ability to manufacture high drug-loaded ASDs. The highest possible drug loadings that still result in a one-phase amorphous system were obtained for bead coating and its predictive intermittent surface coating technique, followed by spray drying and finally by film casting and the continuous surface coating technique, thereby underlining the importance for further research into the underexplored bead coating process. [ABSTRACT FROM AUTHOR]

The physical stability of amorphous solid dispersions (ASD) of active pharmaceutical ingredients (APIs) of high glass forming ability (GFA class III) is generally expected to be high among the scientific community. In this study, the ASD of ten-selected class III APIs with the two polymers, PVPVA 64 and HPMC-E5, have been prepared by spray-drying, film-casting, and their amorphicity at T0 was investigated by modulated differential scanning calorimetry and powder X-ray diffraction. It was witnessed that only five out of ten APIs form good quality amorphous solid dispersions with no phase separation and zero crystalline content, immediately after the preparation and drying process. Hence, it was further established that the classification of an API as GFA class III does not guarantee the formulation of single phase amorphous solid dispersions. [ABSTRACT FROM AUTHOR]