2,9-Diazadibenzoperylene and 2,9-Dimethyldibenzoperylene-1,3,8,10-tetratriflates: Key to Functionalized 2,9-Diazaperopyrenes

The synthesis of 2,9-diaza-1,3,8,10-tetratriflato-dibenzoperylene (DDP 3 a ) and corresponding 2,9-dimethyl-1,3,8,10-tetratriflato-dibenzoperylene (DBP 3 b ) has been developed at multigram scale via reduction of one of the industrially most important high-performance dyes, perylene-3,4,9,10-tetracarboxylic diimide (PTCDI), and of the corresponding dihydroxy peropyrenequinone precursor. The focus of this paper is on the reactivity pattern of 3 a as key intermediate towards highly functionalized 2,9-diazadibenzopyrelenes (DDPs) obtained via catalytic substitution of four triflate by aryl, heteroaryl, alkynyl, aminyl, and O-phosphanyl substituents. The influence of electron-donating substituents (OSiMe₃, OPt-Bu₂, N-piperidinyl), electron-withdrawing (OTf, 3,5-bis-trifluoromethyl-phenyl), and of electron-rich π-conjugated (2-thienyl, 4-tert-butylphenyl, trimethylsilyl-ethynyl) substituents on optoelectronic and structural properties of these functionalized DDPs has been investigated via XRD analyses, UV/Vis, PL spectroscopy, and by electroanalytical CV. These results were correlated to results of DFT and TD-DFT calculations. Thus, functionalized DPPs with easily tunable HOMO and LUMO energies and gap became available via a new and reliable synthetic strategy starting from readily available PTCDI.     

The synthesis and mesomorphic behaviour of the 1,2,4,5-tetrasubstituted benzenes with (4-tridecyloxyphenyl)ethynyl and (4-tridecyloxyphenyl)carbonyloxy substituents

The synthesis, mesophase morphology and transition temperatures of a series of 1,2,4,5-tetrasubstituted benzenes are described. The compounds have (4-tridecyloxyphenyl)carbonyloxy or (4-tridecyloxyphenyl)ethynyl as the peripheral substituents in all possible combinations ranging from the tetra-ester to the tetra-alkyne. Both the substituents used have similar structural dimensions but the greater rigidity of the alkynyl unit ensures that it projects more directly from the central core than does the more flexible ester unit. All of the seven compounds are nematogenic and five show a smectic C phase; the differences observed in the transition temperatures of the compounds are discussed in terms of molecular shape and the relationship of the compounds to appropriate calamitic and discotic systems. Molecular modelling indicates that pi-pi interactions of peripheral phenyl groups can lead to molecules with calamitic shapes.     

Radical polymerization and copolymerization reactivities of fumarates bearing different alkyl ester groups

Radical polymerization of fumarates bearing different alkyl ester groups (DRF) on the same molecules was investigated. In bulk polymerization of DRF at 60°C initiated with 2,2′-azobis(isobutyronitrile), it was confirmed that the polymerization reactivity depended on the structures of both alkyl ester groups. The introduction of bulky alkyl groups increased the polymerization rate and molecular weight of the polymer because of retardation of bimolecular termination rates. The effect of the ester substituents on the termination was examined by electron spin resonance spectroscopy. The copolymerization reactivities of DRF with styrene were also investigated. © 1993 John Wiley & Sons, Inc.     

Ester-functionalized phthalonitriles and zinc phthalocyanines via palladium-catalyzed cyanation of 4,5-dichlorophthalates

Dicyanophthalates 3 were synthesized via Pd-catalyzed two-fold cyanation of the corresponding 4,5-dichlorophthalates with Zn(CN)₂. Appropriate modification of reaction conditions allowed one-pot synthesis of the corresponding zinc phthalocyanines 7 bearing eight peripheral alkyl ester groups. Powder X-ray diffraction study of a mesogenic zinc phthalocyanine bearing branched alkyl substituents revealed a rare case of a transition between two columnar rectangular liquid crystalline mesophases with different symmetry.     

Synthesis of some 2,9-disubstituted-1,10-phenanthrolines

A series of symmetrically disubstituted compounds, with substituents linked to the ring through a carbon atom, has been prepared from 2,9-dimethyl-1,10-phenanthroline. Nmr data are also reported.     

Functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines via stille-type cross-coupling procedures

Stille-type cross-coupling procedures are utilized in order to prepare a variety of functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines. Such N-heterocyclic compounds are of great interest as chelating ligands for transition-metal ions in the field of supramolecular chemistry. Various mono- and disubstitued 2,2'-bipyridines were synthesized in high yields and multigram scales using a modular design principle. The terpyridines may be functionalized in one step with different substituents at the outer pyridine rings and at the 4'-position of the centered ring, leading to multifunctionalized compounds. The initially obtained methyl ester and ethyl ester groups can be simply converted into bromomethyl and hydroxymethyl groups which allow further functionalization reactions.     

Synthesis and spectroscopic DNA binding studies of [Ru(phen)2(tbtc)]2+ and [Ru(2,9-dmp)2(tbtc)]2+

A new polypyridyl ligand tbtc (tbtc=4,5,9,14-tetraaza-benzo[b]triphenylene-11-carboxylic acid methyl ester) and its complexes [Ru(phen)2(tbtc)]2+ (1) (phen=1,10-phenanthroline) and [Ru(2,9-dmp)2(tbtc)]2+ (2) (2,9-dmp=2,9-dimethyl-1,10-phenanthroline) were synthesized and characterized by element analysis, MS, and 1H NMR. The DNA binding properties of both complexes to calf thymus DNA (CT-DNA) were investigated by different spectrophotometric methods and viscosity measurements. The results suggest that both complexes bind to DNA via an intercalative mode, and the DNA binding affinity of complex 1 is much greater than that of complex 2. This difference in binding affinity probably was caused by the different ancillary ligands. Also, when irradiated at 365 nm, complex 1 was found to be a more-effective DNA-cleaving agent than complex 2.     

Intra- and intermolecular thermal transformations of 2-acyl- and 2-alkoxycarbonyl-N-phthalimidoaziridines

Heating 2-acyl- and 2-alkoxycarbonyl-N-phthalimidoaziridines leads to substituted oxazoles in 45-65% yield. Only esters of oxazolecarboxylic acids are formed when the aziridine contains acyl and alkoxy groups. The thermolysis of the same aziridines in the presence of N-phenylmaleimide and the dimethyl ester of acetylenedicarboxylic acid gives both oxazoles and the products of 1,3-dipolar cycloaddition from aziridines with two substituents at the carbon atoms but only oxazoles from trisubstituted aziridines.     

Synthesis and characterization of optical and redox properties of bithiophene-functionalized diketopyrrolopyrrole chromophores

A series of six new 2,2'-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a-f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a-f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.     

Porphyrin-based organogels: control of the aggregation mode by a pyridine-carboxylic acid interaction

To find a new strategy for designing porphyrin-based organogelators, hydrogen-bond-donating (carboxylic acid)/accepting (pyridine) substituents or electron-donating (dialkylamino)/withdrawing (pyridine) substituents were introduced into peripheral positions of a porphyrin (1cp or 1ep, respectively), and the gelation properties were compared with those of symmetrical reference compounds bearing two pyridyl substituents or two ester groups (1pp or 1ee, respectively). It was found that the symmetrical molecules show a solubility that is quite inferior to that of 1cp and 1ep having a dipole moment and precipitate from most organic solvents. 1cp, 1ep, and 1ee formed gels with cyclohexane, methylcyclohexane, and several alcoholic solvents, but scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that their superstructures constructed in the organogels are very different. In cyclohexane, 1cp resulted in a sheetlike structure, whereas 1ep and 1ee resulted in a fiberlike structure. The difference is attributed to the two-dimensional interactive forces in 1cp consisting of the porphyrin-porphyrin pi-pi stacking and the carboxylic acid-pyridine hydrogen bonding. In fact, when the hydrogen-bonding interaction was weakened by alcoholic solvents or by adding pyridine or N,N-(dimethylamino)pyridine, the sheetlike structure was transfigured to the fiberlike structure. Further detailed analyses of their aggregation modes were conducted by spectroscopic methods such as ultraviolet-visible (UV-vis) absorption, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD). On the basis of these findings, the influence of these peripheral substituents on the gel formation and the aggregation mode was discussed.     

Oxidation of 2,9‐Diphenyl‐1,10‐phenanthroline to Generate the 5,6‐Dione and Its Subsequent Alkylation Product

One group of ligands used in transition metal complexes is synthesized by derivatizing 1,10‐phenanthroline. These metal complexes are of interest for study in the field of photovoltaic devices and solar fuels. Previous strategies for obtaining the 5,6‐diones of substituted 1,10‐phenanthrolines do not work for 2,9‐diphenyl‐1,10‐phenanthroline due to undesired products resulting from oxidation of the phenyl substituents. However, 2,9‐diphenyl‐1,10‐phenanthroline‐5,6‐dione can be obtained in reasonable yield by oxidation with BrO₃^? in weak aqueous acid. The resulting dione can be converted directly to the 5,6‐dialkoxy product upon two electron reduction in aprotic solvent followed by treatment with appropriate alkylating agents.     

Steric Crowding and Redox Reactivity in Platinum(II) and Platinum(IV) Complexes Containing Substituted 1,10-Phenanthrolines

The effect of the phenanthroline substituents on the structure and reactivity of platinum(II) and platinum(IV) complexes has been investigated. The X-ray crystal structures of the compounds [PtI(2)(4,7-Ph(2)phen)].CHCl(3) (1dz.CHCl(3)), [PtI(4)(4,7-Ph(2)phen)].CHCl(3) (2dz.CHCl(3)), [PtI(2)(2,9-Me(2)-4,7-Ph(2)phen)] (1fz), and [PtI(4)(2,9-Me(2)-4,7-Ph(2)phen)].I(2) (2fz.I(2)) have shown that complexes 1fz and 2fz, containing ortho-substituted phenanthrolines, exhibit a remarkable displacement of the equatorial iodine atoms from the N-Pt-N' plane (average 0.477(2) and 0.199(2) ?, respectively), a bending of the phenanthroline [angle between outer rings of 19.9(7) and 14.2(7) degrees, respectively] and a rotation of the N-C-C'-N' plane with respect to the N-Pt-N' plane [32.3(10) and 26.5(9) degrees, respectively]. Comparison between the structures of 1fz and 2fz, both having the phenanthroline with methyl substituents in the ortho position, indicates that, in the latter case, because of the presence of the two axial iodine ligands, the displacements of the ligands from the equatorial plane are smaller and find a compensation in a narrowing of the I(1)-Pt-I(1') angle (5 degrees ) and a lengthening of the Pt-N bonds (0.07 ?). The electrochemical behavior of the four-coordinate platinum(II) complexes shows that compounds possessing regular planar geometry have access to the one-electron reduced species, whereas those with distorted coordination geometry are irreversibly reduced by collapsing of the complex geometry. This is in sharp contrast with the behavior of related nickel complexes for which the pseudo-tetrahedral coordination imposed by bulky 2,9-substituents of phenanthroline stabilizes the nickel(I) species. Spectroscopic results allow us to assign a significant Pt(I) character to [1d](-) monoanions. The electrogenerated, plus one electron, complexes are not indefinitely stable and, because of conjugation with the phen ligand, progressively restore the Pt(II) oxidation state by transferring the electron to the peripheral organic ligand. The latter process can involve multiple electron additions in the macroelectrolysis time scale. The related platinum(IV) complexes [PtX(4)(L)] undergo irreversible two-electron reduction accompanied by fast release of the axial ligands and formation of the corresponding platinum(II) species.     

Regioselective,Asymmetric Formal Hydroamination of Unactivated Internal Alkenes

We report the regioselective and enantioselective formal hydroamination of unsymmetrical internal alkenes catalyzed by a copper catalyst ligated by DTBM‐SEGPHOS. The regioselectivity of the reaction is controlled by the electronic effects of ether, ester, and sulfonamide groups in the homoallylic position. The observed selectivity underscores the influence of inductive effects of remote substituents on the selectivity of catalytic processes occurring at hydrocarbyl groups, and the method provides direct access to various 1,3‐aminoalcohol derivatives with high enantioselectivity.     

Regioselective,Asymmetric Formal Hydroamination of Unactivated Internal Alkenes

We report the regioselective and enantioselective formal hydroamination of unsymmetrical internal alkenes catalyzed by a copper catalyst ligated by DTBM‐SEGPHOS. The regioselectivity of the reaction is controlled by the electronic effects of ether, ester, and sulfonamide groups in the homoallylic position. The observed selectivity underscores the influence of inductive effects of remote substituents on the selectivity of catalytic processes occurring at hydrocarbyl groups, and the method provides direct access to various 1,3‐aminoalcohol derivatives with high enantioselectivity.     

Oligomeric cadmium-phthalocyanine complexes: novel supramolecular free radical structures

Certain cadmium-metallated phthalocyanines give rise to EPR active triple-decker sandwich complexes containing two Cd ions and three phthalocyanine (Pc) ligands. These have been shown to form when the ligands bear either eight non- peripheral alkyl or alkenyl substituents or eight peripheral 2-ethylhexyl groups. They can be derived either from three equivalents of a cadmium phthalocyanine precursor or from a 2:1 mixture of a cadmium phthalocyanine (CdPc) and a metal-free phthalocyanine (H(2)Pc). The mode of their formation has been investigated by a series of "cross" experiments. The results indicate that the triple-decker structures are formed by a self-assembly process. This is deduced from results that show that they can disassemble and reassemble with incorporation of differently substituted ligands derived from either an H(2)Pc or CdPc. The reassembled structures in these cross experiments can contain more than one ligand that originated from either the added CdPc or, and more surprisingly, the H(2)Pc compound. Mass spectrometry has also established that higher order oligomers can be formed when steric requirements between the alkyl substituents on adjacent rings in the stack are reduced. Thus an isotopic cluster for a Cd(5)Pc(6) complex has been observed when the eight peripheral substituents are hexyl chains and tetrameric complexes are formed when two different ligands are incorporated within a stack, with one carrying substituents at the peripheral sites and the other bearing substituents at the non-peripheral sites.     

Synthesis and antihypertensive activity of 1,4-dihydropyridine derivatives with a 4-(disubstituted phenyl) ring and an aminoalkyl ester group: highly potent and long-lasting calcium antagonists.

New 1,4-dihydropyridine derivatives bearing a 4-(disubstituted phenyl) ring and an aminoethyl ester or an amino-2,2-dimethyl-propyl ester were synthesized and their antihypertensive activities were examined in normotensive rats and spontaneously hypertensive rats. The effects of phenyl substituents and ester groups on the antihypertensive activity are discussed. Several compounds showed a more potent antihypertensive activity than nicardipine and most compounds had a longer duration of action. Among them, 7B.HCl (TC-81) showed highly potent and long-lasting activity and was selected as a candidate for further pharmacological investigations.     

Bicyclo[3.3.1]nonane-2,9-dione derivatives

Conclusions Bicyclo[3.3.1]nonane-2,9-dione derivatives, containing substituents in the 7 position, were synthesized by the condensation of the morpholine enamines of 4-substituted cyclohexanones with acryloyl chloride.Translated from Izvestiya Akadeinii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1408–1410, June, 1976.     

Synthesis of α-carboxy-γ-butyrolactones by rearrangement of capto-dative cyclopropanes on silica surfaces

The rearrangement of some cyclopropanes featuring electron-withdrawing and electron releasing substitu-ents on vicinal carbons of the trimethylene ring to α-carboxy-γ-lactones upon contact with silica gel at room temperature has been discovered. One or two alkyl ester groups were chosen as electron attractor substitu-ents while one or two cyclopropyl units were used for the release of electron density. It was observed that the lactone forming process is strongly dependent upon these substituents to the extent that only two ester groups and at least one cyclopropane will confer enough vulnerability to the tetra-substituted cyclopropane for the rearrangement to take place. A comparative study of the lactonization by means of contact with silica and alkaline hydrolysis was performed and some mechanistic considerations are put forth.     

Structural and photophysical studies of Cu(NN)2+ systems in the solid state. Emission at last from complexes with simple 1,10-phenanthroline ligands

For a variety of reasons, relating the photophysical properties of a copper phenanthroline to a structure in solution is problematic. To elucidate some of the issues involved, in this paper we describe the crystal and molecular structures of a series of Cu(NN)2(+)-containing systems along with spectral data obtained from the solids themselves. The NN ligands investigated are tmp (3,4,7,8-tetramethyl-1,10-phenanthroline), dpdmp (2,9-diphenyl-4,7-dimethyl-1,10-phenanthroline), dptmp (2,9-diphenyl-3,4,7,8-tetramethyl-1,10-phenanthroline), and dipp (2,9-diisopropyl-1,10-phenanthroline). The results show that a flattening distortion can have a large impact on the spectroscopic properties of a Cu(NN)2+ system, whereas a typical rocking distortion has comparatively little effect. The reflectance spectra of orange or orange-red salts that have approximately perpendicular phenanthroline ligands exhibit absorption bands in the neighborhood of 460 nm along with a shoulder at longer wavelength. In the other limit, when a pronounced flattening distortion occurs and the dihedral angle between ligands is 20 degrees or more off perpendicular, the reflectance spectrum exhibits two distinct visible bands with intense absorption occurring at 525 nm or even longer wavelength. If the phenanthroline ligand lacks bulky substituents in the 2,9 positions, the compound may even be purple, depending on the counterion. Cu(NN)2+ complexes that contain phenyl substituents in the 2,9 positions and exhibit long-wavelength absorption in solution probably adopt a flattened structure in the ground electronic state. In most other systems ground-state flattening is a solid-state effect induced by lattice forces. However, a flattening distortion is an intrinsic attribute of the emissive excited state, although intra- or intermolecular forces can inhibit the effect. In the case of the Cu(dptmp)2+ system, intramolecular steric interactions oppose flattening because the methyl groups in the 3,8 positions control the torsion angles of the neighboring phenyl groups. In the case of [Cu(tmp)2]BPh4, packing interactions induce a small flattening in the crystal, but they also constrain the degree of distortion that can occur in the excited state. As a consequence [Cu(tmp)2]BPh4 exhibits a weak photoluminescence in the solid phase (tau = 15 ns). This is the first report of emission from a bis(phenanthroline)copper(I) system that does not have bulky substituents in the 2 and/or 9 positions of the ligand. The [Cu(tmp)2]BPh4 system crystallizes in space group P2(1)/n with a = 17.4883(4) A, b = 9.86860(10) A, c = 26.3747(6) A, alpha = 90 degrees, beta = 97.7021(8) degrees, gamma = 90 degrees, V = 4510.8(3) A3, and Z = 4. For 12,948 unique data with Fo2 > 2 sigma(Fo2), R = 6.5%. The [Cu(dpdmp)2]PF6 system crystallizes in space group P2/n with a = 16.0722(13) A, b = 8.1100(7) A, c = 16.8937(10) A, alpha = 90 degrees, beta = 93.947(5) degrees, gamma = 90 degrees, V = 2196.8(5) A3, and Z = 2. For 2833 unique data with Fo2 > 2 sigma(Fo2), R = 6.0%. The [Cu(dptmp)2]PF6.THF system crystallizes in space group P1 with a = 12.8486(4) A, b = 13.7341(1) A, c = 15.1678(3) A, alpha = 99.5819(14) degrees, beta = 96.7263(13) degrees, gamma = 97.3311(12) degrees, V = 2591.3(2) A3, and Z = 2. For 13,753 unique data with Fo2 > 2 sigma(Fo2), R = 7.4%. Finally, the [Cu(dipp)2]TFPB system crystallizes in space group P1 with a = 14.2523(3) A, b = 16.0496(4) A, c = 17.5801(3) A, alpha = 112.4150(13) degrees, beta = 105.7480(13) degrees, gamma = 99.6078(11) degrees, V = 3408.7(3) A3, and Z = 2. For 8774 unique data with Fo2 > 2 sigma(Fo2), R = 9.3%.     

New disc-shaped mesogens based on pentakis(phenylethynyl)benzene derivatives

First examples of amphiphilic alkyl pentakis(phenylethynyl)benzene ethers containing functional groups at the terminal position of their alkoxy chains were synthesized by etherification of pentabromophenol with 11-bromoundecan-1-ol and 11-bromoundecanoic acid ethyl ester, respectively, and subsequent palladium catalyzed, fivefold coupling reactions with the substituted phenylacetylene. Two undecanoic acid derivatives with different pentakis(phenylethynyl)phenoxy substituents in the ω-position were prepared by ester cleavage from the corresponding ethyl esters. The thermal behaviours of five penta-alkynes in their pure states, as well as of their charge transfer complexes formed from mixtures with 2,4,7-tri-nitrofluorenone, were examined.