The design of self oxidation-resistant catalytic materials based on organic molecules, although advantageous due to the ability to control their structures, is limited by the presence of labile C–H bonds. This mini review summarizes recent work aimed at first-row transition metal complexes of a new class of coordinating ligands, fluoroalkyl-substituted fluorophthalocyanines, R[Formula: see text]Pcs, ligands in which all, or the majority of their C–H bonds are replaced by a combination of fluoro- and perfluoroalkyl groups yielding porphyrin-bioinspired catalyst models. In the case of homogeneous systems, cobalt(II) complexes catalyze the aerobic oxidation of thiols to disulfides, a reaction of both biological significance and industrial importance. Zinc(II) complexes photo-generate excited state singlet oxygen, [Formula: see text]O[Formula: see text], resulting in both the incorporation of O[Formula: see text] in C–H bonds or, depending on the reaction parameters, oxidation of dyes, model pollutants. Catalyst heterogenization using oxidic and other supports yields stable, active hybrid materials. Functionalized R[Formula: see text]Pcs with acidic (–COOH) or basic (–NH[Formula: see text]R[Formula: see text], [Formula: see text] 2) groups exhibit scaffolds that afford both conjugation with biological vectors for theranostic applications as well as solid-supported materials with superior stability. Electrodes modified with hybrid R[Formula: see text]Pc-containing supports have also been used in photo-oxidations, replacing enzymes and H[Formula: see text]O[Formula: see text] associated reagents with a combination of light and air. An analytical device employed for the nano-level detection of environmentally deleterious antibiotics has been constructed.
Polyfluorinated and perfluorinated compounds in the environment are a growing health concern. 19 F-detected variants of commonly employed heteronuclear shift correlation experiments such as heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) are available; 19 F-detected experiments that employ carbon-carbon homonuclear coupling, in contrast, have never been reported. Herein, we report the measurement of the 1 J CC and n J CC coupling constants of a simple perfluorinated phthalonitrile and the first demonstration of a 19 F-detected 1,1-ADEQUATE experiment.
Optimum molecular substitution in organic thin films is established to facilitate electron and ion transport and, thereby, fast reversible electrochromic switching.
Dye-sensitized TiO2 has found many applications
for
dye-sensitized solar cells (DSSC), solar-to-chemical energy conversion,
water/air purification systems, and (electro)chemical sensors. We
report an electrochemical system for testing dye-sensitized materials
that can be utilized in photoelectrochemical (PEC) sensors and energy
conversion. Unlike related systems, the reported system does not require
a direct electron transfer from semiconductors to electrodes. Rather,
it relies on electron shuttling by redox mediators. A range of model
photocatalytic materials were prepared using three different TiO2 materials (P25, P90, and PC500) and three sterically hindered
phthalocyanines (Pcs) with electron-rich tert-butyl
substituents (t-Bu4PcZn, t-Bu4PcAlCl, and t-Bu4PcH2). The materials were compared with previously developed TiO2 modified by electron-deficient, also sterically hindered
fluorinated phthalocyanine F64PcZn, a singlet oxygen (1O2) producer, as well as its metal-free derivative,
F64PcH2. The PEC activity depended on the redox
mediator, as well as the type of TiO2 and Pc. By comparing
the responses of one-electron shuttles, such as K4Fe(CN)4, and 1O2-reactive electron shuttles,
such as phenol, it is possible to reveal the action mechanism of the
supported photosensitizers, while the overall activity can be assessed
using hydroquinone. t-Bu4PcAlCl showed
significantly lower blank responses and higher specific responses
toward chlorophenols compared to t-Bu4PcZn due to the electron-withdrawing effect of the Al3+ metal center. The combination of reactivity insights and the need
for only microgram amounts of sensing materials renders the reported
system advantageous for practical applications.
We report the synthesis, redox and photo-physical properties, as well as singlet oxygen reactivity of the first representatives of Group III perfluoroalkyl perfluoro metal phthalocyanines, gallium and indium complexes. Microwave-assisted synthesis was used to produce F[Formula: see text]PcM, M [Formula: see text] Ga, In in reasonable yields. Both Ga and In complexes exhibit high thermal and chemical stability properties, attributed to the perfluoroalkyl perfluoro phthalocyanine ligand. Electrochemical and spectroelectrochemical measurements show reversible redox processes for both compounds, including spontaneous re-oxidations following electrochemical or photochemical reductions. No electrochemical or chemical oxidations of the neutral complexes are observed. Photo-hydroperoxidation of ([Formula: see text]-(-)-citronellol occurs with rates of 13.5 and 1.7 [Formula: see text]mol O2 min[Formula: see text] mol[Formula: see text] Pc and substrate turnovers of 225 and 28.2 mmol ([Formula: see text]-Cit s[Formula: see text] mol[Formula: see text] Pc for the In and Ga complexes, respectively. The solid state materials are stable and can be sublimed at temperatures higher than 380°C. Related complexes are candidates for similar chemistry and photophysics based on the observation that the fluorinated ligand determines most of the favorable properties.
Perfluoro phthalonitrile substituted separately with perfluoroalkyl (EWG) and NH2, NHMe, and NMe2 (EDG) groups generate a series of aromatic C-H bonds-free nitriles that can now lose electrons, whose HOMO–LUMO gap is narrowed by EDG beyond the level induced by EWG, and whose dipole moments double. Molecular parameters vary linearly with Hammett’s free-energy constants, their electronic underpinning being uncovered by DFT calculations. The phthalonitriles’ assembling in solid-state structures is determined by forces that transition from van der Waals, in the case of EWG, to H-bonding and/or [Formula: see text]-stacking interactions in the case of EDG, as revealed by their single-crystal X-ray structures.
The recently reported 19F‐detected dual‐optimized inverted 1JCC 1,n‐ADEQUATE experiment and the previously reported 1H‐detected version have been modified to incorporate J‐modulation, making it feasible to acquire all 1,1‐ and 1,n‐ADEQUATE correlations as well as 1JCC and nJCC homonuclear scalar couplings in a single experiment. The experiments are demonstrated using N,N‐dimethylamino‐2,5,6‐trifluoro‐3,4‐phthalonitrile and N,N‐dimethylamino‐3,4‐phthalonitrile.
Modification of the recently reported 19 F-detected 1,1-ADEQUATE experiment that incorporates dual-optimization to selectively invert a wide range of 1 J CC correlations in a 1,n-ADEQUATE experiment is reported. Parameters for the dual-optimization segment of the pulse sequence were modified to accommodate the increased size of 1 J CC homonuclear coupling constants of poly-and perfluorinated molecules relative to protonated molecules to allow broadband inversion of the 1 J CC correlations. The observation and utility of isotope shifts are reported for the first time for 1,1-and 1,n-ADEQUATE correlations.
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