Phenanthroline Ring System Research Articles

6-Nitro-1,10-phenanthrolin-5-amine

In the title compound, C12H8N4O2, the dihedral angle between the phenanthroline ring system and the nitro group is 23.75 (14)°. The molecule features intramolecular N—H...O and C—H...O hydrogen bonds. In the crystal, N—H...(N,N), C—H...N and C—H...O hydrogen bonds link the molecules into [100] chains.

Electronic structure and NH-tautomerism of a novel metal-free phenanthroline-annelated phthalocyanine

A novel low-symmetry A3B-type phthalocyanine annelated with a pyrazino[2,3-f]phenanthroline ring system and substituted with six solubilizing diisopropylphenoxy-groups (1) was synthesized by metal-free DBU-promoted cross-condensation of diiminoisoindolines derived from 4,5-bis(diisopropylphenoxy)phthalonitrile and pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile. The use of these particular precursors affords A3B phthalocyanine in 15% yield, while cross-condensation of the corresponding dinitriles yields only trace amounts of the target compound. Comparative studies of the A3B-type phthalocyanine and its symmetrical octa(diisopropylphenoxy)-substituted counterpart 2 reveal striking differences in the Q band regions of their UV–visible absorption (UV–Vis) spectra, which could be readily rationalized through a comparison with calculated TD-DFT spectra. Since 1 can have two NH-tautomers with equivalent and non-equivalent NH-groups, and DFT calculations predict that the former tautomer is only 2.3 kcal/mol more stable than the latter one, a comprehensive analysis of 13C NMR spectra was carried out through the application of 1H13C HMBC and HSQC techniques. It demonstrated that only the tautomer with equivalent NH-groups is present in solution.

Electrochemical and DFT study of the reduction of substituted phenanthrolines

The irreversible electrochemical reduction data of a series of free uncoordinated differently substituted phenanthrolines is presented. Electron withdrawing chloride substituents in the 4,7 ring positions increase the reduction potential by 0.3V, while electron donating methyl substituents lead to a lowering of reduction potential relative to unsubstituted 1,10-phenanthroline. Linear relationships are obtained between the reduction potential of free uncoordinated differently substituted phenanthrolines and density functional theory (DFT) calculated LUMO (lowest unoccupied molecular orbital) energies, electron affinities, global electrophilicity indexes and Mulliken electronegativities. The reduction potential of 4,7-diphenyl-1,10-phenanthroline deviates slightly from the linear trend, since the phenyl groups donate electron density to the phenanthroline ring system through both π-resonance and σ-inductive effects. This enables the phenanthroline ring system to more readily accept an electron at a higher, less negative potential than is otherwise the case. On the contrary, the non-aromatic substituents (e.g. Me, NH2 and Cl) withdraw/donate electron density from/to the phenanthroline ring system through σ-inductive effects only. Linear relationships are also obtained between the reduction potential of the series of phenanthroline free ligands and the formal reduction potential of corresponding metal-phenanthroline complexes.

3,4,7,8-Tetramethyl-1,10-phenanthrolin-1-ium nitrate monohydrate

In the crystal of the title compound, C16H17N2 +·NO3 −·H2O, the tetra­methyl-1,10-phenanthrolinium cations, nitrate anions and lattice water mol­ecules are all located on a mirror plane with the methyl H atoms of the cation equally disordered over two sites about the mirror plane. The cation, anion and water mol­ecule are linked by O—H⋯O and N—H⋯O hydrogen bonds into a sheet parallel to the bc plane. π–π stacking between phenanthroline ring systems is observed in the crystal structure, the centroid–centroid distance being 3.4745 (6) Å.

(2,9-Dimethyl-1,10-phenanthroline-κ2N,N′)diiodidocadmium

In the title compound, [CdI2(C14H12N2)], the mol­ecule sits on a crystallographic twofold axis. The coordination sphere of the CdII atom is built of two symmetry-equivalent N atoms of one 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and two symmetry-equivalent I atoms, thus forming a distorted tetra­hedral geometry. Inversion-related mol­ecules inter­act along the c-axis direction by π–π stacking inter­actions between the phenanthroline ring systems, with centroid–centroid distances of 3.707 (9) and 3.597 (10) Å.

Di-μ-glutarato-κO:O-bis-[aqua-(1,10-phenanthroline-κN,N')copper(II)

In the centrosymmetric dinuclear title complex, [Cu2(C5H6O4)2(C12H18N2)2(H2O)2], the CuII atom displays a dis­torted square-pyramidal coordination environment with the basal plane occupied by two phenanthroline N atoms and two O atoms from different glutarate dianions while a water mol­ecule is located at the apical position. Of the two water H atoms, one is engaged in an intra­molecular hydrogen bond with a free oxygen of the dianion whereas the second is engaged in an inter­molecular hydrogen bond, building a corrugated layer parallel to (100). These layers are further connected through π–π stacking inter­actions involving symmetry-related phenanthroline rings [centroid–centroid distance = 3.5599 (17) and 3.5617 (18) Å], building a three dimensionnal network. C—H⋯π inter­actions involving the phenanthroline ring system are also observed.

2,9-Bis(3,5-dimethyl-1H-pyrazol-1-yl-κN2)-1,10-phenanthroline-κ2N,N′](methanol-κO)(nitrito-κ2O,O′)cadmium(II) perchlorate

In the title complex, [Cd(NO2)(C22H20N6)(CH3OH)]ClO4, the CdII ion is in a distorted penta­gonal–bipyramidal CdN4O3 coordination geometry. The dihedral angles formed between the mean planes of the pyrazole rings and the phenanthroline ring system are 4.37 (19) and 5.84 (21)°. In the crystal, the anions and cations are connected by inter­molecular O—H⋯O hydrogen bonding, while pairs of weak inter­molecular C—H⋯O hydrogen bonds connect the cations into centrosymmetric dimers. In addition, there is a π–π stacking inter­action involving two symmetry-related benzene rings, with a centroid–centroid distance of 3.437 (3) Å.

6,7-Dihydro-3H-1,4-diazepino[1,2,3,4-lmn][1,10]phenanthroline-3,9(5H)-dione

In the title compound, C15H12N2O2, the seven-membered ring bearing the three methyl­ene C atoms displays a puckered conformation, with the methyl­ene C atoms deviating from the plane of the benzene ring by 0.05 (1), 0.98 (1) and 1.04 (1) Å. The phenanthroline unit is not planar; the dihedral angles between this benzene ring and the other pyridyl rings are 9.62 (4) and 9.31 (4)°. The crystal packing is stabilized by π–π inter­actions between two phenanthroline ring systems, forming a centrosymmetric dimer with a centroid–centroid distance of 3.656 (1) Å.

4,7-Diphenyl-2,9-bis(trichloromethyl)-1,10-phenanthroline

In the title compound, C26H14Cl6N2, the phenanthroline ring system is essentially planar, with an r.m.s. deviation of 0.048 (6) Å, and makes dihedral angles of 64.8 (14) and 66.6 (6)° with the two terminal phenyl rings. One of the trichloro­methyl groups is disordered over two positions, with occupancies of 0.42 (2) and 0.58 (2).

3-(1H-Imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzonitrile methanol solvate

In the title compound, C20H11N5·CH3OH, the benzene ring is twisted by a small dihedral angle of 1.89 (11)° with respect to the imidazo[4,5-f][1,10]phenanthroline ring system. N—H⋯O and O—H⋯N hydrogen bonding is present in the crystal structure.

2-Hydroxybenzyl alcohol–phenanthroline (1/1)

Crystals of the title compound, C12H8N2·C7H8O2, were obtained during cocrystallization experiments of a compound with two hydrogen-bond donors (2-hydroxy­benzyl alcohol) with another compound containing two hydrogen-bond acceptors (phenanthroline). Unexpectedly, the two mol­ecules do not form dimers with two O—H⋯N hydrogen bonds connecting the two mol­ecules. However, one of the hydr­oxy groups forms a bifurcated hydrogen bond to both phenanthroline N atoms, whereas the other hydr­oxy group forms an O—H⋯O hydrogen bond to a symmetry-equivalent 2-hydroxy­benzyl alcohol mol­ecule. In addition, the crystal packing is stabilized by π–π inter­actions between the two phenanthroline ring systems, with a centroid–centroid distance of 3.570 Å.

2,9-Bis(4-pyridylmethoxy)-1,10-phenanthroline

In the title mol­ecule, C24H18N4O2, the dihedral angles between the mean plane of the phenanthroline ring system and the pyridine rings are 82.52 (5) and 71.58 (4)°. The dihedral angle between the two pyridine ring planes is 53.54 (6)°. In the crystal structure, there are π–π stacking inter­actions between 1,10-phenanthroline rings, with centroid–centroid distances of 3.6101 (11) and 3.5864 (11) Å.

Dichlorido(2,9-dipropoxy-1,10-phenanthroline-κ2N,N′)cadmium(II)

In the title complex, [CdCl2(C18H20N2O2)], the CdII ion is coordinated by two N atoms from a bis-chelating 2,9-diprop­oxy-1,10-phenanthroline ligand and two Cl atoms in a distorted tetra­hedral environment. The two Cd—Cl bond distances are significantly different from each other and the N—Cd—N bond angle is acute. In the crystal structure, there are π–π stacking inter­actions between symmetry-related phenanthroline ring systems, with a centroid–centroid distance of 3.585 (3) Å.

2-(2,4,6-Trimethylphenyl)-1,10-phenanthroline

In the title mol­ecule, C21H18N2, the mean plane of the benzene ring of the mesityl group forms a dihedral angle of 82.69 (4)° with that of the phenanthroline ring system. The crystal structure is stabilized by π–π stacking inter­actions between the phenanthroline system and the benzene ring of the mesityl group of a symmetry-related mol­ecule, with centroid–centroid distances of 3.7776 (14) and 3.7155 (13) Å.

Catena-Poly[[(2,9-dieth-oxy-1,10-phen-anthroline-κN,N')cadmium(II)]-di-μ-dicyan-amido-κN:N

In the title polymer, [Cd(C2N3)2(C16H16N2O2)]n, the CdII ion is coordinated by two N atoms from one 2,9-dieth­oxy-1,10-phenanthroline mol­ecule and four N atoms from four symmetry-related dicyanamide ions in a distorted octa­hedral geometry. In the 2,9-dieth­oxy-1,10-phenanthroline ligand, the O and C atoms of the eth­oxy groups are located almost in the plane defined by the phenanthroline ring system. Two dicyanamide ions bridge two CdII ions, which are located on a twofold axis, forming a one-dimensional zigzag chain along the [001] direction. The 2,9-dieth­oxy-1,10-phenanthroline mol­ecules act as bidentate terminal ligands. There are π–π inter­actions between polymeric chains, characterized by a centroid–centroid distance of 3.7624 (2) Å between the phenanthroline rings of two neighbouring chains.

μ-Aqua-κ2O:O-di-μ-4-methylbenzoato-κ4O:O′-bis[(4-methylbenzoato-κO)(1,10-phenanthroline-κ2N,N′)nickel(II)

In the title dinuclear complex, [Ni2(C8H7O2)4(C12H8N2)2(H2O)], each NiII atom is six-coordinated by three carboxylate O atoms from three 4-methyl­benzoate ligands, two N atoms from two 1,10-phenanthroline ligands, and one μ2-bridging aqua ligand. The dimeric complex is located on a crystallographic twofold axis and each Ni atom displays a distorted octa­hedral coordination geometry. The crystal structure is stabilized via intra­molecular hydrogen bonding of the bridging water mol­ecule and the uncoordinated carboxyl­ate O atoms, and by C—H⋯O and π–π stacking inter­actions [centroid–centroid distances between neighbouring phenanthroline ring systems and between the benzene ring of a 4-methyl­benzoate unit and a phenanthroline ring system are 3.662 (2) and 3.611 (3) Å, respectively].

(2,9-Dimethoxy-1,10-phenanthroline-κ2N,N′)nitratosilver(I)

In the crystal structure of the title compound, [Ag(NO3)(C14H12N2O2)], the AgI centre is three-coordinated by two N atoms from 2,9-dimeth­oxy-1,10-phenanthroline and one O atom of the nitrate anion. The Ag—N bond lengths are almost identical, and O—Ag—N bond angles are larger than the bite angle N—Ag—N. In the main ligand, the O and C atoms of the meth­oxy groups lie almost in the plane defined by the phenanthroline ring system. Based on the extended delocal­ized π system of phenanthroline and the d10 electronic configuration of the metal centre, the title complex is expected to produce strong luminescent emission when properly excited.

2,9-Dimethyl-1,10-phenanthrolinium nitrate

The title compound, C14H13N2+·NO3−, is a protonated amine salt compound. A nitrate ion acts as hydrogen-bond acceptor of N—H⋯O and C—H⋯O hydrogen bonds, connecting the cations and anions into layers running parallel to the ab plane. The packing is additionally stabilized by π–π inter­actions between phenanthroline ring systems.

Aquadichloro(2,9-dimethyl-1,10-phenanthroline-κ2 N,N′)nickel(II)

In the title compound, [NiCl2(C14H12N2)(H2O)], there are two molecules in the asymmetric unit. Each Ni atom is five-coordinate in a geometry between trigonal–bipyramidal and tetragonal–pyrimidal. Molecules are linked into a three-dimensional framework by O—H...Cl and C—H...Cl hydrogen bonds. The packing is further stabilized by π–π interactions between the phenanthroline ring systems.

Aquadichloro(2,9-dimethyl-1,10-phenanthroline-κ2N,N)copper(II)

In the title compound, [CuCl2(C14H12N2)(H2O)], there are two mol­ecules in the asymmetric unit; both Cu atoms are five-coordinate with a distorted trigonal-bipyramidal geometry. Mol­ecules are linked into a three-dimensional network by O—H⋯Cl and C—H⋯Cl hydrogen bonds. The packing is stabilized by π–π inter­actions between the phenanthroline ring systems.