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The tuning of the luminescent properties of PtII complexes for possible use in organic light-emitting diodes (OLEDs) and sensing applications is commonly achieved by altering the electronic properties of the ligands. Our group recently demonstrated that the trifluoropropynyl ligand is strongly electron-withdrawing and possibly useful for blueshifting emission. Herein, we report the synthesis of two complexes of this trifluoropropynyl ligand, namely PtLC2CF3 and PtLFC2CF3 (L = 1,3-di(2-pyridyl)benzene; LF = 4,6-difluoro-1,3-di(2-pyridyl)benzene). The PtLC2CF3 complex crystallized in the monoclinic space group P21/n with Z = 4. The PtLFC2CF3 complex crystalized in the triclinic space group P-1 with Z = 2. Changing the tridentate ligand from L to LF resulted in a change in the packing structure, with the latter showing a metallophilic interaction (Pt-Pt distance = 3.3341(3) Å). The solution photophysics of the trifluoropropynyl complexes is compared with that of the corresponding Cl complexes, PtLCl and PtLFCl. Replacement of the chloro ligand with the trifluoropropynyl ligand blueshifted the monomer emission by less than 5 nm but blueshifted the excimer emission peaks by 15–20 nm. The complexes of the trifluoropropynyl ligand also favor the excimer emission more than the complexes of the chloro ligand. The excimer emission is quenched by dissolved oxygen significantly more than the corresponding monomer emission. The excimer emission and monomer emission are well separated, and the ratio of monomer to excimer emission is strongly dependent on oxygen concentration. [ABSTRACT FROM AUTHOR]

The luminescent properties of Au(I) and Pt(II) compounds are commonly tuned by exploiting the alkynyl ligand with varying electron density. Herein, we describe the synthesis of three new emissive transition metal compounds, tbpyPt(C2pym)2, Ph3PAuC2pym, and Cy3PAuC2pym (where HC2pym = 2-ethynylpyrimidine), verified by 1H-NMR, EA, and a single-crystal X-ray diffraction analysis. The tbpyPt(C2pym)2 complex crystallized as an Et2O solvate in the orthorhombic space group Pbca with Z = 24 with three unique Pt(II) species within the unit cell. The Cy3PAuC2pym species crystallizes in a monoclinic space group with one unique complex in the asymmetric unit. Changing the identity of the phosphine from Cy3P to Ph3P influences interactions within the unit cell. Ph3PAuC2pym, which also crystalizes in a monoclinic space group, has an aurophilic bonding interaction Au–Au distance of 3.0722(2) Å, which is not present in crystalline Cy3PAuC2pym. Regarding optical properties, the use of an electron-deficient heterocycle provides an alternate approach to blue-shifting the emission of Pt(II) transition metals' compounds, where the aryl moiety is made more electron-deficient by exploiting nitrogen within this moiety instead of the typical strategy of decorating the aryl ring with electron withdrawing substituents (e.g., fluorines). This is indicated by the blue-shift in emission that occurs in tbpyPt(C2pym)2 (λmax, emission = 512 nm) compared to the previously reported tbpyPt(C22-py)2 (where HC22-py = 2-ethynylpyridine) complex (λmax, emission = 520 nm). [ABSTRACT FROM AUTHOR]

4-(tris(4-methyl-1H-pyrazol-1-yl)methyl)aniline was prepared in a 63% yield utilizing a C–F activation strategy from a mixture of 4-(trifluoromethyl)aniline, 4-methylpyrazole, and KOH in dimethylsulfoxide (DMSO). The identity of the product was confirmed by nuclear magnetic resonance spectroscopy, infrared spectroscopy, mass spectrometry, and single-crystal analysis. An analysis of crystals grown from the layering method (CH2Cl2/acetone/pentane) indicated two distinct polymorphs of the title compound. Moreover, density functional theory calculations utilizing the MN15L density functional and the def2-TZVP basis set indicated that 4-(tris(4-methyl-1H-pyrazol-1-yl)methyl)aniline forms with similar energetics to the previously reported unmethylated analog. [ABSTRACT FROM AUTHOR]

Three new compounds, namely, 5‐fluorocytosine–urea (2/1), 2C4H4FN3O·CH4N2O, (I), 5‐fluorocytosine–5‐fluorocytosinium 3,5‐dinitrosalicylate–water (2/1/1), 2C4H4FN3O·C4H5FN3O+·C7H2N2O7−·H2O, (II), and 2‐amino‐4‐chloro‐6‐methylpyrimidine–6‐chloronicotinic acid (1/1), C6H4ClNO2·C5H6ClN3, (III), have been synthesized and characterized by single‐crystal X‐ray diffraction. In compound (I), 5‐fluorocytosine (5FC) molecules A and B form two different homosynthons [R22(8) ring motif], one formed via N—H...O hydrogen bonds and the second via N—H...N hydrogen bonds. In addition to this interaction, a sequence of fused‐ring motifs [R21(6), R33(8), R22(8), R43(10) and R22(8)] are formed, generating a supramolecular ladder‐like hydrogen‐bonded pattern. In compound (II), 5FC and 5‐fluorocytosinium are linked by triple hydrogen bonds, generating two fused‐ring motifs [R22(8)]. The neutral 5FC and protonated 5‐fluorocytosinum cation form a dimeric synthon [R22(8) ring motif] via N—H...O and N—H...N hydrogen bonds. On either side of the dimeric synthon, the neutral 5FC, 5‐fluorocytosinium cation, 3,5‐dinitrosalicylate anion and water molecule are hydrogen bonded through N—H...O, N—H...N, N—H...OW and OW—HW...O hydrogen bonds, forming a large ring motif [R1010(56)], leading to a three‐dimensional supramolecular network. In compound (III), 2‐amino‐4‐chloro‐6‐methylpyrimidine (ACP) interacts with the carboxylic acid group of 6‐chloronicotinic acid via N—H...O and O—H...O hydrogen bonds, generating an R22(8) primary ring motif. Furthermore, the ACP molecules form a base pair via N—H...N hydrogen bonds. The primary motif and base pair combine to form tetrameric units, which are further connected by Cl...Cl interactions. In addition to this hydrogen‐bonding interaction, compounds (I) and (III) are further enriched by π–π stacking interactions. [ABSTRACT FROM AUTHOR]

Four salts, namely, 2,4,6‐triaminopyrimidinium 6‐chloronicotinate dihydrate, C4H8N5+·C6H3ClNO2−·2H2O, (I), 2,4,6‐triaminopyrimidinediium pyridine‐2,6‐dicarboxylate dihydrate, C4H9N52+·C7H3NO42−·2H2O, (II), 2,4,6‐triaminopyrimidinediium sulfate monohydrate, C4H9N52+·SO42−·H2O, (III), and 2,4,6‐triaminopyrimidinium 3,5‐dinitrobenzoate dihydrate, C4H8N5+·C7H3N2O6−·2H2O, (IV), were synthesized and characterized by X‐ray diffraction techniques. Proton transfer from the corresponding acid to the pyrimidine base has occurred in all four crystal structures. Of the four salts, two [(I) and (IV)] exist as monoprotonated bases and two [(II) and (III)] exist as diprotonated bases. In all four crystal structures, the acid interacts with the pyrimidine base through N—H...O hydrogen bonds, generating an R22(8) ring motif. The sulfate group mimics the role of the carboxylate anions. The water molecules present in compounds (I)–(IV) form water‐mediated large ring motifs. The formation of water‐mediated interactions in these crystal structures can be used as a model in the study of the hydration of nucleobases. Water molecules play an important role in building supramolecular structures. In addition to these strong hydrogen‐bonding interactions, some of the crystal structures are further enriched by aromatic π–π stacking interactions [(I) and (II)]. [ABSTRACT FROM AUTHOR]