A new colorimetric molecular sensor allowing for cheap, fast, sensitive, and highly selective naked-eye detection of Hg(2+) in water is described. This molecule combines a 1,8-diaminoanthraquinone signaling subunit and phosphonic acid esters that confer the water solubility to the dye (R = H). A ready-to-use colorimetric solid sensor was obtained by incorporating an amphiphilic analog (R = OC(12)H(25)) exhibiting similar binding properties and optical responses in an agarose film.
A two‐step reaction sequence for accessing meso‐(dialkoxyphosphoryl)porphyrins from readily available trans‐A2‐type porphyrins was developed. This approach involves bromination and subsequent palladium‐catalyzed phosphonylation. Optimal conditions for both steps were identified after exploration of various reaction parameters such as solvent, temperature and catalyst. A series of dialkoxyphosphoryl‐substituted A2B‐porphyrins Zn3(a–g) bearing electron‐donating, electron‐withdrawing or sterically bulky substituents at the meso‐aryl groups were prepared in overall yields close to 40 %. These compounds, being air‐stable and soluble in most organic solvents, are valuable synthetic intermediates because they can be readily transformed into functionalized trans‐A2BC‐type porphyrins through regioselective functionalization at the unsubstituted meso position of the macrocycle. Therefore, this approach offers considerable promise for application to the synthesis of trans‐A2BC‐type porphyrins, including water‐soluble derivatives, push‐pull chromophores and bis(porphyrin)s.
Ru(II) complexes with polypyridyl ligands play a central role in the development of photocatalytic organic reactions. This work is aimed at the structural modification of such complexes to increase their...
International audienceThe synthesis of functionalized porphyrins and their conjugates from meso-tetraarylporphyrins through the acylation and the oxidation of beta-aminoporphyrins was investigated. 2,3-Dioxochlorins were prepared by the oxidation of a variety of beta-aminoporphyrins and subsequently used in a condensation reaction with functionalized aromatic aldehydes and ammonium acetate to form beta-functionalized porphyrins bearing a fused imidazole ring. Under optimized experimental conditions both reactions tolerate various functional groups and afford the products in an appropriate overall yield. The mildness and usefulness of this methodology are illustrated by several examples including the synthesis of porphyrins bearing receptor groups and water-solubilizing moieties
Synthetic approaches to 1,10-phenanthroline-3carboxylic acid (2), 1,10-phenanthroline-3,8-dicarboxylic acid (3) and their functionalized derivatives were investigated. Acids 2 and 3 were prepared in good yields from bromophenanthrolines via palladium-catalyzed alkoxycarbonylation. Moreover, butyl 8-bromo-1,10-phenanthroline-3-carboxylate was obtained in acceptable yield (25-35%) by ceasing the carbonylation of the dibromide 5 after 30-70% consumption of the starting compound. To prepare functionalized derivatives of acids 2 and 3, the reactions of butyl 8-bromo-1,10phenanthroline-3-carboxylate and diethyl 4,7-dichloro-1,10-phenanthroline-3,8-dicarboxylate with various nucleophiles were investigated. S N Ar reactions are suitable for the synthesis of 4,7-diazido-, dimethoxy-and diamino-substituted 3,8-bis(ethoxycarbonyl)phenanthrolines, including the macrocyclic derivatives. The bromine atom at position 8 of the phenanthroline ring reacts with nucleophiles only in the presence of the palladium catalysts. The scope of these reactions was briefly investigated conducting Sonogashira, Suzuki-Miyaura and Hirao reactions. Hydrolysis of the functionalized esters of phenanthroline leads to corresponding acids in good yields.[a] Dr.
Suzuki–Miyaura cross-coupling reaction has been used for the synthesis of tricyclic architectures based on trans-A2B2-porphyrins and bisaminal-protected polyazamacrocycles which are linked directly or by a p-phenylene spacer. This modular approach allowed the synthesis of ligands with various substituted porphyrin macrocycles and bisaminal-protected tetraazamacrocycles possessing different cavity sizes. These molecules can be assembled into dimers using a DABCO linker. Deprotection of these compounds afforded porphyrin-bis(polyazamacrocycle) triads.
The
β-substituted porphyrinoids commonly used to form functional
assembled systems in nature yet are still scarcely used in material
chemistry probably due to the laborious synthesis of these compounds.
In this work, β-octa[(4-diethoxyphosphoryl)phenyl]porphyrin
(2HOPPP) and its metal (Zn(II), Cd(II), Cu(II), and Ni(II))
complexes were prepared in good yields. These highly soluble chromophores
were characterized in solution using spectroscopic (NMR, UV–vis,
fluorescence), electrochemical, and spectroelectrochemical methods.
Attachment of the electron-deficient residue (ArP(O)(OEt)2) to the porphyrin macrocycle leads to easier reductions and harder
oxidations of the macrocycle for all complexes studied as compared
to corresponding meso-tetra[4-(diethoxyphosphoryl)phenyl]porphyrin
derivatives reported previously. We demonstrated that the strong electron-deficient
character of the MOPPP porphyrins results principally
from the increase in the number of electron-withdrawing groups at
the periphery of the tetrapyrrolic macrocycle. Electron-deficient
porphyrins are highly required in supramolecular and material chemistry
in part due to their ability to form supramolecular assemblies via the coordination of axial ligands to the central metal
atom. According to single-crystal X-ray data, ZnOPPP forms
in the crystalline phase dimers in which each of the two tetrapyrrolic
macrocycles is connected through an unusual combination of hydrogen
bonding of two phosphoryl groups and the water molecule axially coordinated to the zinc atom of the partner molecule. The
involvement of water molecules in porphyrin binding allows for an
increase of distance between two porphyrin mean N4 planes,
up to 4.478 Å. The offset of phosphoryl groups attached to the
macrocycle through a 1,4-phenylene spacer withdraws the whole porphyrin
macrocycle of one molecule from spatial overlap with the macrocycle
of a partner molecule and increases the Zn–Zn distance up to
10.372 Å. This still unknown type of porphyrin dimers allows
one to get deeper insights into the organization of naturally occurring
tetrapyrrolic macrocycles. ZnOPPP also forms a labile
dimeric complex in 5.3 × 10–7–5.8 ×
10–5 M chloroform solutions. In contrast, other
complexes prepared in this work exist as monomeric species under these
experimental conditions. The self-association constant of ZnOPPP has been determined by electronic absorption spectroscopy.
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