- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Incremental Introduction of Organocatalytic Activity into Conformationally Engineered Porphyrins
摘要： To study the correlation of macrocycle nonplanarity and catalytic activity of free base porphyrins in detail, a series of six tetraphenylporphyrins with graded degree of β-ethyl substitution ('H2EtxTPPs' 1–6; x = 0, 2, 4, 6, 8) was applied in organocatalyzed reactions. They display incrementally increasing nonplanarity due to repulsive peri-interactions. This creates an out-of-plane vector and better accessibility of the core amine and imine groups as the number of alkyl substituents increases. Following such a molecular engineering approach, the inner core system could be used to activate small molecules as a result of significant saddle distortion. The potential organocatalyst 'H2EtxTPPs' were used in benchmark sulfa-Michael reactions and we found a distinct relationship between nonplanarity and conversion. These observations were attributed to the combined effect of enhanced basicity and increased H-bonding potential that could facilitate bifunctional organocatalysis. Ultimately, density functional theory (DFT) calculations were performed on 1–6 to monitor some electronic properties of the title compounds.
关键词： porphyrins,organocatalysis,hydrogen bonds,molecular engineering,macrocycles
更新于2025-09-23 15:22:29
-
π-Conjugated Macrocyclic Receptor Featuring Redox-Active Viologen Units
摘要： Supramolecular chemistry has recently resulted in the development of highly functional materials and nano-scale molecular machines. Herein, the authors report a macrocyclic receptor 6, featuring two redox-active viologen units. Unlike conventional viologen-based cyclophanes, 6 does not contain ether linkages or chemically labile N-benzylbipyridium bonds, resulting in a more robust system that is fully conjugated.
关键词： macrocycles,viologens,electrochemical receptor
更新于2025-09-23 15:21:01
-
Influence of the meso-substituents of zinc porphyrins in dye-sensitized solar cell efficiency with improved performance under short periods of white light illumination
摘要： The sensitization activity of four zinc metalloporphyrin dyes: meso-tetrakis(4-pyridyl)porphyrinato Zn(II) (a), meso-triphenyl-(4-carboxyphenyl)porphyrinato Zn(II) (b), meso-tetrakis(4-carboxyphenyl)porphyrinato Zn(II) (c) and meso-tripyridyl(4-carboxyphenyl)porphyrinato Zn(II) (d) is reported here, in terms of current-potential curve, open-circuit potential, fill factor, and overall solar energy conversion efficiency which have been evaluated under 100 mW/cm2 light intensity and their performances compared to the benchmark N719 (di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium(II). This work focus the structural aspects of dyes with anchoring groups using TiO2-based Dye Sensitized Solar Cells (DSSCs), which includes pyridyl and carboxyphenyl acid groups and argue how the combination of both anchoring groups, in the same structure, may allow relevant optimization of DSSCs performance in the near future. Also, a noticeable improvement in the photovoltaic performance of all dyes, reaching a maximum increase from 25% to 69% in the overall DSSC efficiency under short periods of white light illumination is discussed.
关键词： Dye sensitized solar cells (DSSCs),Macrocycles,Carboxylic acid anchoring group,Dyes,Photoconversion efficiency,TiO2,Metalloporphyrin
更新于2025-09-23 15:19:57
-
Formation of emissive nanoparticles from tetraphenylethylene-containing boronate macrocycles: preparation, characterization and functionalization
摘要： Formation of emissive nanoparticles from tetraphenylethylene-containing boronate macrocycles: preparation, characterization and functionalization. [2+2] Macrocycles composed of two tetraphenylethylenes (TPEs) and two linkers, namely 1a (R = H) and 1b (R = NO2), were prepared in a facile manner through the one-pot dehydration of gem-di(boronic acid)-appended TPEs 2a (R = H) and 2b (R = NO2) with di(trimethylolpropane) 3 in MeOH. Considering that use of THF instead of MeOH as the reaction solvent gave a mixture of boronate esters, hydrophobicity-induced non-covalent interactions involving mono(boronate ester) intermediates produced by the dehydration of 2 and 3, may be responsible for the selective cyclization in MeOH. We found that these boronate macrocycles formed emissive nanoparticles of 1a (λem = 483 nm, λex = 365 nm, ΦF = 31%) and 1b (λem = 539 nm, λex = 365 nm, ΦF = 11%) in H2O, with average diameters of 312 ± 44.6 nm and 146 ± 25.5 nm, respectively. The dynamic features of these particles endow them with reversible thermoresponsive properties; indeed, emissiveness responded linearly to temperature over the tested range. The hysteresis-free temperature sensitivity (S) of the 1a-based nanoparticles was determined to be 0.75% K?1 in H2O. Such behavior was rationalized by dynamic light scattering (DLS) experiments, which facilitated the detection of particle-size changes in response to temperature. As a control, bis(pinacolboryl)-appended TPE 6, which does not form nanoparticles in H2O, was poorly responsive to changes in temperature. Furthermore, effective emission quenching was observed upon addition of 2,6-dichloro-4-nitroaniline (DCN), a toxic pesticide, at a detection limit of 2.00 ppm in H2O/MeOH (3 : 2 v/v). Although DCN-induced quenching is ascribable to the nature of the TPE units, the self-assembled nanoparticle morphologies were altered upon addition of DCN, as determined by DLS and field-emission scanning electron microscopy (FE-SEM), and appeared to involve an Ostwald ripening process.
关键词： boronate macrocycles,tetraphenylethylene,thermoresponsive,nanoparticles,aggregation-induced emission,chemosensor
更新于2025-09-19 17:15:36
-
Binaphthyl-Based Macrocycles as Optical Sensors for Aromatic Diphenols
摘要： The synthesis of several rigid, homochiral organic macrocycles possessing, respectively, average molecular D2 and D3 symmetries, is described. They have been obtained from aromatic dicarboxylic acids, in combination with an axially-chiral, suitable dibenzylic alcohol, derived from 1,1′-binaphthyl-2,2′-diol (BINOL) using one-pot esterification reactions in good isolated yields. NMR and circular dichroism (CD) spectroscopies detect the structural and shape variability in the scaffolds, reflected both in terms of the changes in chemical shifts and the shape of selected proton resonances, and in terms of the variation of the CD signature related to the dihedral angle defined by the binaphthyl units embedded in the rigid cyclic skeleton. The D2 cyclic adducts are able to form stable complexes with aromatic diphenols, with binding strengths that are dependent on small variations in the spacing units, and therefore on the shapes of the internal cavities of the cyclic structures.
关键词： binaphthyl,macrocycles,chirality,circular dichroism,chiroptical sensors
更新于2025-09-19 17:13:59
-
Effect of the Medium on Fluorescence Parameters and Photostability of Porphyrins of Different Structure
摘要： Fluorescence and photostability against the action of UV irradiation of different porphyrins in benzene, DMF, and acetic acid media have been studied. The effect of the macroheterocycle structure on the conditions of its thermal decomposition under inert atmosphere has been investigated.
关键词： photodecomposition,nonplanar macrocycles,NH-activity,porphyrin,thermal stability
更新于2025-09-09 09:28:46
-
Topological and steric constraints to stabilize heteroleptic copper(I) complexes combining phenanthroline ligands and phosphines
摘要： Heteroleptic copper(I) complexes combining phenanthroline derivatives (NN) and chelating bis-phosphine ligands (PP) are an important class of luminescent materials for various applications. While [Cu(NN)(PP)]+ derivatives are also kinetically unstable. As a result, a dynamic ligand exchange reaction is often observed in solution leading to a dynamic mixture of heteroleptic and homoleptic complexes. In order to prevent the formation of the homoleptic species, macrocyclic phenanthroline ligands have been used for the preparation of [Cu(NN)(PP)]+ pseudo-rotaxanes. The topological constraint resulting from the macrocyclic structure of the NN ligand drives the thermodynamic equilibrium toward the exclusive formation of the heteroleptic complex as long as the macrocycle is large and flexible enough to allow the threading of the PP ligand. In contrast, when the threading is prevented by steric constraints, unprecedented copper(I) complexes with a trigonal coordination geometry are obtained. These results are summarized in the present concept article.
关键词： macrocycles,Pseudo-rotaxanes,copper,phenanthroline ligands,Bis-phosphine ligands
更新于2025-09-04 15:30:14
-
Expanding the Porphycene Core: Modification and Metalation
摘要： Porphycenes, the first structural isomer of porphyrin, display unique chemical and photophysical properties. In this Account, we detail our group’s individual and collaborative efforts in elucidating further the chemical properties of porphycene. Particular emphasis will be placed on recent efforts devoted to expanding the porphycene core.
关键词： expanded porphycenes,porphycene therapeutics,macrocycles,hetero-annulenes,electronic communication,porphycene materials,porphyrinoid,porphycenes,metal complexes,coordination chemistry,expanded porphyrins
更新于2025-09-04 15:30:14