Octa-3,6-hexoxyphthalocyanines: Effect of Protonation on Spectral and Photochemical Properties

Макаров, Д. А.; Derkacheva, V. M.; Kuznetsova, Nina A.; Kaliya, O. L.; Luk’yanets, E. A.

doi:10.6060/mhc130951k

Cited by 9 publications

(6 citation statements)

References 15 publications

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“…Initially, researchers tended to interpret the solvatochromic behavior of α-AlkO-substituted ZnPc complexes in terms of the formation of J-aggregates, via coordination of the α-O atom to the Zn ion of a neighboring molecule. − Indeed, the addition of pyridine to such aggregates could cause their dissociation with the formation of monomeric species. However, some research groups have proposed that this process occurs because of the protonation of molecules. − In particular, in chlorinated solvents, it can be caused by traces of HCl that inevitably form upon storage of CHCl 3 or C 2 H 2 Cl 4 , especially upon exposure to light. The addition of pyridine removes the proton from the Pc molecule, restoring the spectral appearance.…”

Section: Introductionmentioning

confidence: 99%

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

et al. 2016

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A series of novel nonperipherally substituted tetra-15-crown-5-dibutoxyoxanthrenocyanines (H2, Mg, Zn), acting as chameleons with the unique properties of switchable absorption and emission in the near-infrared (NIR) spectral range have been synthesized and characterized by X-ray diffraction. The attachment of 15-crown-5-α-dibutoxyoxanthreno moieties to phthalocyanine is responsible for the high solubility of the resulting molecules and the red shift of the Q band to the NIR region and offers a unique possibility for postsynthetic modification of the optical properties of the molecules. Both aggregation of phthalocyanine and its participation in an acid-base equilibrium strongly alter their optical properties. For example, the absorption of complexes can be reversibly tuned from 686 up to 1028 nm because of the cation-induced formation of supramolecular dimers or subsequent protonation of meso-N atoms orf macrocycle, in contrast to peripherally substituted tetra-15-crown-5-phthalocyanines without oxanthrene moieties. The reversibility of these processes can be controlled by the addition of [2.2.2]cryptand or amines. All investigated compounds exhibit fluorescence with moderate quantum yield, which can also be switched between the ON and OFF states by the action of similar agents.

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Section: Introductionmentioning

confidence: 99%

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

et al. 2016

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“…Consistent with this, the photoluminescent quantum yield for the emission of 2 was similar to 2HCl , at 0.06 in toluene. A previous report on 2 found a similar quantum yield of 0.04 in CH 2 Cl 2 [53] . A previous report of the emission properties of protonated 2 generated in solution recorded a decrease in the quantum yield to 0.01, lower than that observed for the isolated 2HCl [52] .…”

Section: Resultsmentioning

confidence: 62%

“…This bond angle is significantly larger than those typically observed for chloride bridged dimers, which commonly fall between 90–100°, [50,51] likely due to the steric hindrance of the Pc‐ligands to which the Li atoms are coordinated. We have found no other examples of a structurally characterized side‐pocket metallated PcM; all other examples of PcMs hosting side‐pocket cations incorporated either protons or, in one case, N‐methylation [26,32,52,53] . The presence of the axial chloride in 2Li 1.5 Cl 1.5 demonstrates that the formation of a 5‐coordinate Zn metal centre is not dependent on the side‐pocket proton.…”

Section: Resultsmentioning

confidence: 79%

Preferential Formation of Side‐Pocket‐Substituted Zinc Phthalocyanines Emitting Beyond 800 nm

et al. 2021

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A series of zinc (1,4,8,11,15,18,22,25‐octabutoxy)phthalocyanine (2) complexes that spontaneously form 5‐coordinate complexes with anionic axial ligands neutralized with side‐pocket cations, of the form Cation‐PcZnX (X=Cl, OAc; Cation=H+ or Li+), was synthesized and structurally characterized. The side‐pocket protonation of the axial‐chloride species pushed the emission maximum from 760 nm (for axial ligand‐free 2) to 826 nm, well into the NIR region. A 1D‐coordinated chain bridged by lithium and chloride atoms was isolated and structurally characterized, representing the first side‐pocket metalated PcM species. This preferential formation of axially substituted [PcZnX]− “ate” complexes and their sequestration of both protons and lithium cations, opens a new series of materials with unique structural and electronic properties. Furthermore, their ability to both absorb and emit in the NIR region makes them desirable for numerous applications.

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“…The protonation process was found solvent-specific and depends on the stability of the phthalocyanine complex as well as on the strength of the acid used. Basically, the protonated Pc macrocycle is considered less chemically stable [23][24][25][26]. Notably labile compounds (e.g., PbPc, MgPc) do not create stable protonated forms and are subject to prompt demetallation and subsequent cleavage of the Pc moiety, particularly in the presence of strong acids such as H 2 SO 4 [27,28].…”

Section: Introductionmentioning

confidence: 99%

“…TFA is an important versatile acid (less oxidizing than H 2 SO 4 ) used as a reagent in organic synthesis, as an ion pairing agent in HPLC or solvent for NMR spectroscopy, and calibrant in mass spectrometry. It is also extensively used in studies concerning the acidic activation of porphyrins or typical mono-phthalocyanines [26,49,50]. However, in this scope the lanthanide diphthalocyanines thus far were not sufficiently explored.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Bond-Mediated Conjugates Involving Lanthanide Diphthalocyanines and Trifluoroacetic Acid (Lnpc2@TFA): Structure, Photoactivity, and Stability

et al. 2020

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The interaction between lanthanide diphthalocyanine complexes, LnPc2 (Ln = Nd, Sm, Eu, Gd, Yb, Lu; Pc = C32H16N8, phthalocyanine ligand) and trifluoroacetic acid (TFA) was investigated in benzene, and the stability of the resulting molecular system was assessed based on spectral (UV-Vis) and kinetic measurements. Structural Density Functional Theory (DFT) calculations provided interesting data regarding the nature of the bonding and allowed estimating the interaction energy between the LnPc2 and TFA species. Conjugates are created between the LnPc2 and TFA molecules via hydrogen bonds of moderate strength (>N∙∙H··) at the meso- -bridges of the Pc moieties, which renders the sandwich system to flatten. Attachment of TFA is followed by rearrangement of electronic density within the chromophore system of the macrocycles manifested in considerable changes in their UV-Vis spectra and consequently the color of the studied solutions (from green to orange). The LnPc2@TFA conjugates including Nd, Sm, Eu, and Gd appeared evidently less photostable when exposed to UV radiation than the related mother compounds, whereas in the case of Yb and Lu derivatives some TFA-prompted stabilizing effect was noticed. The conjugates displayed the capacity for singlet oxygen generation in contrast to the LnPc2s itself. Photon upconversion through sensitized triplet–triplet annihilation was demonstrated by the TFA conjugates of Nd, Sm, Eu, and Gd.

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Octa-3,6-hexoxyphthalocyanines: Effect of Protonation on Spectral and Photochemical Properties

Cited by 9 publications

References 15 publications

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

Preferential Formation of Side‐Pocket‐Substituted Zinc Phthalocyanines Emitting Beyond 800 nm

Hydrogen Bond-Mediated Conjugates Involving Lanthanide Diphthalocyanines and Trifluoroacetic Acid (Lnpc2@TFA): Structure, Photoactivity, and Stability

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