Synthesis, structural investigations and magnetic properties of dipyridinated manganese phthalocyanine, MnPc(py)2

DFT-D3 and TD-DFT Studies of the Adsorption and Sensing Behavior of Mn-Phthalocyanine toward NH3, PH3, and AsH3 Molecules

This study employs density functional theory (DFT) calculations at the B3LYP/6-311+g(d,p) level to investigate the interaction of XH3 gases (X = N, P, As) with the Mn-phthalocyanine molecule (MnPc). Grimme's D3 dispersion correction is applied to consider long-range interactions. The adsorption behavior is explored under the influence of an external static electric field (EF) ranging from -0.514 to 0.514 V/Å. Chemical adsorption of XH3 molecules onto the MnPc molecule is confirmed. The adsorption results in a significant decrease in the energy gap (Eg) of MnPc, indicating the potential alteration of its optical properties. Quantum theory of atoms in molecules (QTAIM) analysis reveals partially covalent bonds between XH3 and MnPc, and the charge density differenc (Δρ) calculations suggest a charge donation-back donation mechanism. The UV-vis spectrum of MnPc experiences a blue shift upon XH3 adsorption, highlighting MnPc's potential as a naked-eye sensor for XH3 molecules. Thermodynamic calculations indicate exothermic interactions, with NH3/MnPc being the most stable complex. The stability of NH3/MnPc decreases with increasing temperature. The direction and magnitude of the applied electric field (EF) play a crucial role in determining the adsorption energy (Eads) for XH3/MnPc complexes. The Eg values decrease with an increasing negative EF, which suggests that the electrical conductivity (σ) and the electrical sensitivity (ΔEg) of the XH3/MnPc complexes are influenced by the magnitude and direction of the applied EF. Overall, this study provides valuable insights into the suggested promising prospects for the utilization of MnPc in sensing applications of XH3 gases.

Tuning the visible colour of octahedral manganese(III) phthalocyanines via axial ligand exchange

A series of [PcMnL2]SbF6 complexes (Pc = phthalocyanine) was synthesized and structurally characterized by stripping the chloride from PcMnCl with AgSbF6 in o-dichlorobenzene and adding a range of donor ligands (L = THF, pyridine, p-dimethylaminopyridine (DMAP), Ph3PO, N-methylimidazole (MeIm), MeCN) to the resulting solution. Addition of or exposure to water where L = heterocyclic amines yielded μ-oxo complexes of the form [PcMnL]2O, which were structurally characterized for L = DMAP and MeIm. The [PcMnL2]SbF6 complexes have an increased solubility in organic solvents, where the axial ligands inhibit the characteristic ring π-π aggregation of PcM complexes. A variety of colours were observed (blue/green to red/purple), with Q-band absorptions (excluding the μ-oxo species) spanning from 715-761 nm and LMCT-bands from 497-574 nm. The combination of the ligand-induced absorption shifts coupled with their relative intensities in the visible region is responsible for the observed colour range and illustrates that facile ligand exchange is a useful tool in producing materials with a variety of colours from PcMnCl.

Trinuclear coordination assemblies of low-spin dicyano manganese(II) (S = 1/2) and iron(II) (S = 0) phthalocyanines with manganese(II) acetylacetonate, tris(cyclopentadienyl)gadolinium(III) and neodymium(III)

The reaction of Mn^IIPc, Fe^IIPc or Fe^IIPcCl₁₆ with KCN in the presence of cryptand[2.2.2] yielded dicyano-complexes {cryptand(K⁺)}₂{M^II(CN)₂(macrocycle^2-)}^2-·XC₆H₄Cl₂ (M = Mn and Fe, X = 1 and 2) that were used for the preparation of trinuclear assemblies of the general formula {cryptand(K⁺)}₂{M^II(CN)₂Pc·(ML)₂}^2-·nC₆H₄Cl₂ (M^II = Mn^II and Fe^II; n = 1, 4 and 5). These assemblies were formed via coordination of two manganese(II) acetylacetonate (ML = Mn^II(acac)₂, S = 5/2), tris(cyclopentadienyl)gadolinium (ML = Cp₃Gd^III, S = 7/2) or tris(cyclopentadienyl)neodymium (ML = Cp₃Nd^III, S = 3/2) units to the nitrogen atoms of bidentate cyano ligands. The N(CN)-Mn{Mn^II(acac)₂} bond is 2.129(3) Å long but the bonds are elongated to 2.43-2.49 Å for tris(cyclopentadienyl)lanthanides. {Cryptand(K⁺)}₂{Mn^II(CN)₂Pc·(Mn^II(acac)₂)₂}^2-·5C₆H₄Cl₂ (2) contains three Mn(II) ions in different spin states (S = 5/2 and 1/2). Strong antiferromagnetic coupling of spins observed between them with the exchange interaction (J) of -17.6 cm^-1 enables the formation of a high S = 9/2 spin state for {Mn^II(CN)₂Pc·(Mn^II(acac)₂)₂}^2- dianions at 2 K. The estimated exchange interaction between Mn^II (S = 1/2) and Gd^III (S = 7/2) spins in {Mn^II(CN)₂Pc·(Cp₃Gd^III)₂}^2- is only -1.1 cm^-1, and in contrast to 2, nearly independent Gd^III and Mn^II centers are formed. As a result, no transition to the high-spin state is observed in {Mn^II(CN)₂Pc·(Cp₃Gd^III)₂}^2-. The {Mn^II(CN)₂Pc·(Cp₃Nd^III)₂}^2- and{Fe^II(CN)₂Pc·(Cp₃Nd^III)₂}^2- dianions with Cp₃Nd^III show a decrease of χ_MT values in the whole studied temperature range (300-1.9 K). A similar behaviour was found previously for pristine Cp₃Nd^III and Cp₃Nd^III·L complexes (L = alkylisocyanide ligand).

Coordination-induced metal-to-macrocycle charge transfer and effect of cations on reorientation of the CN ligand in the {SnL2Mac}2− dianions (L = CN−, OCN−, Im−; Mac = phthalo- or naphthalocyanine)

Anionic coordination {crypt(M⁺)}₂{SnL₂Mac}²⁻ complexes of tin(ii) phthalo- (Pc) and naphthalocyanines (Nc) were obtained and discussed.

Coordination Complexes of Titanium(IV) and Indium(III) Phthalocyanines with Carbonyl-Containing Dyes: The Formation of Singly Bonded Anionic Squarylium Dimers

Reduction methods for the preparation of coordination complexes of titanium(IV) and indium(III) phthalocyanines (Pc) with organic dyes such as indigo, thioindigo, and squarylium dye III (SQ) have been developed, which allow one to obtain crystalline {cryptand(K⁺ )}{(cis-indigo-O,O)^2- Ti^IV (Pc^2- )}(Cl^- )⋅C₆ H₄ Cl₂ (1), {cryptand(K⁺ )}{(cis-thioindigo-O,O)^2- In^III (Pc^2- )}^- ⋅C₆ H₄ Cl₂ (2), and {cryptand(K⁺ )}{[(SQ)₂ -O,O]^2- In^III (Pc^2- )}^- ⋅3.5 C₆ H₄ Cl₂ (3) complexes. The formation of these complexes is accompanied by the reduction of the starting dyes to the anionic state. Transition of trans-indigo or trans-thioindigo to the cis conformation in 1 and 2 provides coordination of both carbonyl oxygen atoms of the dye to Ti^IV Pc or In^III Pc. SQ is reduced to the radical anion state and forms unusual diamagnetic singly bonded (SQ^- )₂ dimers in 3. These dimers have two closely positioned carbonyl oxygen atoms coordinated to In^III Pc. Dianionic Pc^2- macrocycles have been found in 1-3. The complexes contain two chromophore molecules at one metal center. However, their optical spectra are defined mainly by absorption bands of the metal phthalocyanines.

Effect of the Substitution Pattern (Peripheral vs Non-Peripheral) on the Spectroscopic, Electrochemical, and Magnetic Properties of Octahexylsulfanyl Copper Phthalocyanines

In order to investigate the substitution position effect on the spectroscopic, electrochemical, and magnetic properties of copper phthalocyanines, a detailed structure-property analysis has been performed by examining two copper phthalocyanines that are octasubstituted by hexylsulfanyl chains respectively in the peripheral (Cu-P) and non-peripheral (Cu-NP) positions. Cu-NP showed a marked near-IR maximum absorption compared to Cu-P and, accordingly, a smaller HOMO-LUMO energy gap, calculated via the electrochemical results and simulations in the gas phase, as well as for Cu-NP from its crystallographic data. An electron-spin resonance (ESR) technique is used to extract the g values from the powder spectra that are taken at room temperature. The g values were determined to be g_∥ = 2.160 and g_⊥ = 2.045 for Cu-P and g_∥ = 2.150 and g_⊥ = 2.050 for Cu-NP. These values indicate that the paramagnetic copper center in both phthalocyanines has axial symmetry with a planar anisotropy ( g_∥ > g_⊥). The ESR spectra in solution could be obtained only for Cu-P. Curie law is used to fit the experimental data of the magnetic susceptibility versus temperature graphs, and the Curie constant ( C) and diamagnetic/temperature-independent paramagnetic (α) contributions are deduced as 0.37598 (0.39576) cm³·K/mol and -23 × 10^-5 (25 × 10^-5) cm³/mol respectively for Cu-P and Cu-NP. The room temperature magnetic moment value (1.70 μ_B) is close to the spin-only value (1.73 μ_B) for the peripheral complex, showing that there is no orbital contribution to μ_eff. In contrast, at room temperature, the value of the magnetic moment (1.77 μ_B) is above the spin-only value, showing an orbital contribution to the magnetic moment. Cu-NP's room temperature magnetic moment value is larger than the value for Cu-P, demonstrating that the orbital contribution to the magnetic moment depends upon the substituent position. The magnitudes of the effective magnetic moment values also support that both Cu-P and Cu-NP complexes have square-planar coordination. This result is consistent with the determined g values. The spin densities were determined experimentally, and the results suggest that the positions of the substituents affect these values (0.469 for Cu-P and 0.490 for Cu-NP).

Synthesis and properties of N-methylimidazole solvates of vanadium(ii), chromium(ii) and iron(ii) phthalocyanines. Strong NIR absorption in VII(MeIm)2(Pc2−)

Crystal structures and optical and magnetic properties of N-methylimidazole (MeIm) solvates of vanadium(ii), chromium(ii) and iron(ii) phthalocyanines have been studied.

Synthesis and purification of metallooctachlorophthalocyanines

A detailed synthetic procedure based on the use of urea, dichlorophthalic acid, respective transition metal halides and [NH4]2[MoO4] as a catalyst in the melt or by using 1,2,4-trichlorobenzene as a high-boiling inert solvent is described to gain 2,3,9,10,16,17,23,24-metallooctachlorophthalocyanines (MPcCl8 compounds with M=Mn, Fe, Co, Ni, Cu). In cases that a first purification by subsequent treatment of the crude materials with HCl, NaOH and HCl would not give rise to analytically pure compounds, a second novel purification by using pyridine is described. The degree of purity, exceeding always 98%, is determined by thermogravimetric analysis. Comparative IR, UV/Vis and PXRD studies of the MPcCl8 compounds are reported.

Photophysical and nonlinear optical study of benzothiazole substituted phthalocyanines in solution and thin films

In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (I[Formula: see text][X[Formula: see text]]) and hyperpolarizability ([Formula: see text] at 4.61 × 10[Formula: see text] esu and 3.44 × 10[Formula: see text] esu, respectively, with a low I[Formula: see text] value of 0.06 J.cm[Formula: see text]

Synthesis, magnetic and spectroscopic studies of a Schiff base derived from cephaclor and 1,2-diaminobenzene and its transition metal complexes

M(II) coordination compounds of Mn, Fe, Co and Ni with a Schiff base (HL) derived from the condensation of cephaclor antibiotic with 1,2-diaminobenzene were synthesized and characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The analytical and molar conductance values indicated that the chloride ions coordinate to the metal ions. Based on these studies, the general formulae [M(L)Cl(H2O)] (M(II)=Mn, Fe, Co, Ni) are proposed for the complexes. The ligand HL behaves as a monoanionic tetradentate NNNO chelating agent.

DFT Study of Unligated and Ligated ManganeseII Porphyrins and Phthalocyanines

A theoretical study of the electronic structure, bonding, and properties of unligated and ligated manganese(II) porphyrins and phthalocyanines has been carried out "in detail" using a density functional theory (DFT) method. While manganese tetraphenylporphine (MnTPP) in the crystal is high spin (S = 5/2) with the Mn(II) atom out of the porphyrin plane, the present calculations find that the free manganese porphine (MnP) molecule has no obvious tendency to distort from planarity even in the high-spin state. The ground state of the planar structure is found to be intermediate spin (S = 3/2). Manganese phthalocyanine (MnPc) is calculated to have a 4E(g) ground state, in agreement with the more recent magnetic circular dichroism (MCD) and UV-vis measurements of the molecule in an argon matrix but different from the early magnetic measurements of solid MnPc. The effect of the crystal structure on the electronic state of MnPc is examined by the calculations of a model system. For the six-coordinate adducts with two pyridine (py) ligands, the strong-field axial ligands raise the energy of the Mn d(z2)-orbital, thereby making the Mn(II) ion low spin (S = 1/2). The recent assignment of MnPc(py)2 as an intermediate-spin state proves to be incorrect. Some issues involved in the reduced products have also been clarified. Five-coordinate MnP(py) and MnPc(py) complexes are high spin and intermediate spin, respectively.