Inverse Hypercorroles

Ground-state and time-dependent density functional theory (TDDFT) calculations with the long-range-corrected, Coulomb-attenuating CAMY-B3LYP exchange-correlation functional and large, all-electron STO-TZ2P basis sets have been used to examine the potential "inverse hypercorrole" character of meso-p-nitrophenyl-appended dicyanidocobalt(III) corrole dianions. The effect is most dramatic for 5,15-bis(p-nitrophenyl) derivatives, where it manifests itself in intense NIR absorptions. The 10-aryl groups in these complexes play a modulatory role, as evinced by experimental UV-visible spectroscopic and electrochemical data for a series of 5,15-bis(p-nitrophenyl) dicyanidocobalt(III) corroles. TDDFT (CAMY-B3LYP) calculations ascribe these features clearly to a transition from the corrole's a2u-like HOMO (retaining the D4h irrep used for metalloporphyrins) to a nitrophenyl-based LUMO. The outward nature of this transition contrasts with the usual phenyl-to-macrocycle direction of charge transfer transitions in many hyperporphyrins and hypercorroles; thus, the complexes studied are aptly described as inverse hypercorroles.

Synthesis, fabrication of self-assembled film and ambipolar chemical sensing properties of triple-decker (phthalocyaninato) (porphyrinato) europium complex

A mixed (phthalocyaninato) (porphyrinato) europium triple-decker complex, named (TPyP)Eu[Formula: see text][Pc(OC[Formula: see text]H[Formula: see text]][Formula: see text][TPyP [Formula: see text] dianion of 5,10,15,20-tetra(4-tert-pyridyl) porphyrin, Pc(OC[Formula: see text]H[Formula: see text] 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninate] is synthesized and characterized by MALDI-TOF, 1HNMR, UV-visible spectra and differential pulse voltammetry techniques. Introduction of electron-donating butoxy groups at the periphery of the phthalocyanine ligands and electron-withdrawing pyridyl substituents onto the meso-positions of the porphyrin ring not only increases the solubility of the triple decker but successfully tunes the HOMO and LUMO energy levels into a soluble ambipolar organic semiconductor. A simple quasi-Langmuir–Shäfer (QLS) method is used to fabricate self-assembled film of (TPyP)Eu[Formula: see text][Pc(OC[Formula: see text]H[Formula: see text]][Formula: see text]. Excellent sensitivity, reproducible [Formula: see text]-type and [Formula: see text]-type responses to electron-accepting gas NO[Formula: see text] and electron-donating gas NH[Formula: see text] are found for the films of (TPyP)Eu[Formula: see text][Pc(OC[Formula: see text]H[Formula: see text]][Formula: see text]complex at room temperature. The detection limit towards NO[Formula: see text] and NH[Formula: see text] is as low as 0.4 ppm and 1 ppm, respectively, with percentage current change of 4.2% and 1.6%, depending on the uniform molecular packing and intermolecular interactions among the triple decker molecules. The present results represent not only the excellent example of ambipolar triple-decker phthalocyanine-based sensors obtained by a solution-based method, but more importantly provide a new strategy for the molecular design to obtain soluble ambipolar organic semiconductors in sensing device fabrication.

Spectroscopic characterization of free-base hydroxy(arylethynyl)porphyrins in acidic and basic media

The addition of arylethynyl groups to the porphyrin macrocycle represents an effective strategy with which to enhance the light-harvesting properties of porphyrins. We now extend this modification to arylethynyl porphyrins with two or four [Formula: see text]-hydroxyphenyl substituents. Arylethynyl porphyrins bearing four, but not two, [Formula: see text]-hydroxyphenyl substituents show evidence of aggregation under acidic conditions. Under basic conditions, deprotonation of the peripheral hydroxyphenyl substituents results in substantially red-shifted spectral features and enhanced absorption in the Q-band region. When the hydroxyphenyl groups are appended to the porphyrin macrocylce via the ethynyl spacers, the spectral shifts observed upon deprotonation are significantly enhanced relative to those observed for hydroxyphenylporphyrins, highlighting the role of expanded conjugation in altering porphyrin photophysics.

Solvent and substituent effects on UV-vis spectra and redox properties of zinc p-hydroxylphenylporphyrins

A series of zinc[Formula: see text]-hydroxylphenylporphyrins was synthesized and characterized by spectroscopic and electrochemical methods in four different nonaqueous solvents. The investigated compounds are represented as [([Formula: see text]-HOPh)[Formula: see text](ptBuPh)[Formula: see text]P]Zn, where P represents the dianion of a porphyrin, Ph represents a phenyl group, HO and [Formula: see text]Bu are para substituents on the meso-phenyl rings of the macrocycle and [Formula: see text] = 0–4. The four utilized nonaqueous solvents were dichloromethane (CH[Formula: see text]Cl[Formula: see text], NN-dimethylformamide (DMF), dimethylsulfoxide (DMSO) and pyridine (Py) which were selected on the basis of their coordinating capabilities. The UV-visible spectra and redox potentials of each porphyrin were analyzed both as a function of Hammett substituent constants for groups at the para-positions of the meso-phenyl rings and as a function of the Gutmann solvent donor number which is related to the coordinating ability of the solvent. Each porphyrin exhibits two reductions in CH[Formula: see text]Cl[Formula: see text], DMSO and Py while three reductions are observed in DMF, the additional reaction being due to a phlorin product generated in solution after formation of the porphyrin dianion. Two or three reversible oxidations were seen in CH[Formula: see text]Cl[Formula: see text], the exact number depending upon the specific porphyrin and the presence of [Formula: see text]-OH substituents at the meso-phenyl rings of the compound. The first two oxidations were assigned as involving the conjugated macrocycle and the third is associated with oxidation of the meso-HOPh group(s).

Organometallic Group 11 (CuIII , AgIII , AuIII ) Complexes of a trans-Doubly N-Confused Porphyrin: An "Expanded Imidazole" Structural Motif

Complexation of group 11 metal cations with an α-bis(phenylthio)-substituted trans-doubly N-confused porphyrin (trans-N₂ CP_SPh : 4) afforded a series of square-planar trivalent organometallic complexes (i.e., Cu-H4, Ag-H4, and Au-H4). The X-ray crystal structures of the complexes revealed highly planar core geometries along with the presence of peripheral amine and imine nitrogen sites of the pyrrolic moieties. NMR, UV/Vis absorption, and magnetic circular dichroism (MCD) spectroscopies suggested the 18 π-electron aromaticity of the complexes. The aromaticity was also fully analyzed by various theoretical methodologies such as nucleus-independent chemical shift (NICS) and anisotropic induced current density (ACID) calculations. The central metal affects the amphiprotic character of the complexes possessing both pyrrolic amino nitrogen and imino nitrogen atoms at the periphery, which was examined by the photometric titration with trifluoroacetic acid (TFA) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), respectively. The inherent acidity of the complexes was followed in the order; Cu-H4>Au-H4>Ag-H4 and that of basicity was Au-H4>Ag-H4>Cu-H4. The complexes could be considered as an "expanded imidazole" structural motif.

Colorimetric “naked eye” detection of CN−, F−, CH3COO−and H2PO4−ions by highly nonplanar electron deficient perhaloporphyrins

Highly nonplanar electron deficient perhaloporphyrins were utilized for the detection of basic anions such as CN⁻, F⁻, CH₃COO⁻and H₂PO₄⁻viaanion induced deprotonation. These sensors can be reusable without loss of their sensing ability.