Diamondoid-Type Copper Coordination Polymers Containing Soft Cyclodiphosphazane Ligands

Three novel coordination polymers have been synthesized by reacting <i>cis</i>- and <i>trans</i>-alkyne-appended cyclodiphosphazanes with CuX (X = Br, I) salts. The reaction of <i>cis</i>-[(PhCCP)₂(μ-N^<i>t</i>Bu)₂] (<b>1</b>) with CuBr in a 1:3 molar ratio gave a 3D coordination polymer, [{Cu₄­(μ₃-Br)₄}­{(<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂)­Cu₄­(μ₂-Br)₄­(<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂)}₄]_<i>n</i> (<b>3</b>), having diamondoid topology with an unprecedented copper alkyne coordination, whereas the reaction of <b>1</b> with CuI in a 1:4 molar ratio afforded a 1D polymeric complex, [{Cu₄­(μ₃-I)₄}­(NCCH₃)₂­{<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂}₂]_<i>n</i> (<b>4</b>). In contrast, the reaction of <i>trans</i>-[(PhCCP)₂(μ-N^<i>t</i>Bu)₂] (<b>2</b>) with CuI was found to be independent of stoichiometry and afforded a 3D coordination polymer, [{Cu₄­(μ₃-I)₄}­{<i>trans</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂}₂]_<i>n</i> (<b>5</b>), exclusively

Novel zeotype frameworks with soft cyclodiphosphazane linkers and soft Cu₄X₄ clusters as nodes

Two novel cyclodiphosphazane cluster frameworks with Cu₄X₄ clusters as tetrahedral nodes and ferrocenyl cyclodiphosphazanes [Fe(η5-C5H₄)₂(PNtBu)₂] as ditopic linkers have been synthesized. These frameworks having sodalite topology display a unique integration of porosity and redox activity and offer new opportunities for the synthesis of zeotype frameworks with soft phosphorus-based ligands

Construction of the First Rhodium(I) Cyclic Pentameric Structure [Rh(CO)Cl{(μ‑N^<i>t</i>BuP)₂(CCPh)₂}]₅ Using (Phenylethynyl)cyclodiphosphazanes

To examine the steric effect of the phosphorus substituents in cyclodiphosphazanes, two less sterically demanding alkynyl-functionalized <i>cis</i>-[(μ-N^<i>t</i>BuP)₂(CCPh)₂] (<b>1</b>) and <i>trans</i>-[(μ-N^<i>t</i>BuP)₂(CCPh)₂] (<b>2</b>) were synthesized. The cis isomer <b>1</b>, with a large subtending angle (135.8°) upon treatment with [Rh­(CO)₂Cl]₂, afforded the first rhodium­(I) cyclic pentameric macrocycle [Rh­(CO)­Cl­{(μ-N^<i>t</i>BuP)₂(CCPh)₂}]₅ (<b>3</b>). The crystal structure of the cyclic pentamer <b>3</b> closely resembles a classical “Ferris wheel”

Diamondoid-Type Copper Coordination Polymers Containing Soft Cyclodiphosphazane Ligands

Three novel coordination polymers have been synthesized by reacting <i>cis</i>- and <i>trans</i>-alkyne-appended cyclodiphosphazanes with CuX (X = Br, I) salts. The reaction of <i>cis</i>-[(PhCCP)₂(μ-N^<i>t</i>Bu)₂] (<b>1</b>) with CuBr in a 1:3 molar ratio gave a 3D coordination polymer, [{Cu₄­(μ₃-Br)₄}­{(<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂)­Cu₄­(μ₂-Br)₄­(<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂)}₄]_<i>n</i> (<b>3</b>), having diamondoid topology with an unprecedented copper alkyne coordination, whereas the reaction of <b>1</b> with CuI in a 1:4 molar ratio afforded a 1D polymeric complex, [{Cu₄­(μ₃-I)₄}­(NCCH₃)₂­{<i>cis</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂}₂]_<i>n</i> (<b>4</b>). In contrast, the reaction of <i>trans</i>-[(PhCCP)₂(μ-N^<i>t</i>Bu)₂] (<b>2</b>) with CuI was found to be independent of stoichiometry and afforded a 3D coordination polymer, [{Cu₄­(μ₃-I)₄}­{<i>trans</i>-(PhCCP)₂­(μ-N^<i>t</i>Bu)₂}₂]_<i>n</i> (<b>5</b>), exclusively

Water-Soluble Pd₈L₄ Self-assembled Molecular Barrel as an Aqueous Carrier for Hydrophobic Curcumin

A tetrafacial water-soluble molecular barrel (<b>1</b>) was synthesized by coordination driven self-assembly of a symmetrical tetrapyridyl donor (<b>L</b>) with a <i>cis</i>-blocked 90° acceptor [<i>cis</i>-(en)­Pd­(NO₃)₂] (en = ethane-1,2-diamine). The open barrel structure of (<b>1</b>) was confirmed by single crystal X-ray diffraction. The presence of a hydrophobic cavity with large windows makes it an ideal candidate for encapsulation and carrying hydrophobic drug like curcumin in an aqueous medium. The barrel (<b>1</b>) encapsulates curcumin inside its molecular cavity and protects highly photosensitive curcumin from photodegradation. The photostability of encapsulated curcumin is due to the absorption of a high proportion of the incident photons by the aromatic walls of <b>1</b> with a high absorption cross-sectional area, which helps the walls to shield the guest even against sunlight/UV radiations. As compared to free curcumin in water, we noticed a significant increase in solubility as well as cellular uptake of curcumin upon encapsulation inside the water-soluble molecular barrel (<b>1</b>) in aqueous medium. Fluorescence imaging confirmed that curcumin was delivered into HeLa cancer cells by the aqueous barrel (<b>1</b>) with the retention of its potential anticancer activity. While free curcumin is inactive toward cancer cells in aqueous medium at room temperature due to negligible solubility, the determined IC₅₀ value of ∼14 μM for curcumin in aqueous medium in the presence of the barrel (<b>1</b>) reflects the efficiency of the barrel as a potential curcumin carrier in aqueous medium without any other additives. Thus, two major challenges of increasing the bioavailability and stability of curcumin in aqueous medium even in the presence of UV light have been addressed by using a new supramolecular water-soluble barrel (<b>1</b>) as a drug carrier

Comparison of Two Phosphinidenes Binding to Silicon(IV)dichloride as well as to Silylene

The cyclic alkyl­(amino) carbene (cAAC) anchored silylene with two phosphinidenes was isolated as (cAAC)­Si­{P­(cAAC)}₂ (<b>3</b>) at room temperature, which was synthesized from the reduction of (Cl₂)­Si­{P­(cAAC)}₂ (<b>2</b>) using 2 equiv of KC₈. Compound <b>2</b> resulted from the reaction of 2 equiv of (cAAC)­PK (<b>1</b>) with 1 equiv of SiCl₄. Compounds <b>2</b> and <b>3</b> are the first examples where two terminal phosphinidenes are binding each to a silicon center characterized by single crystal X-ray structural analysis. Furthermore, the structure and bonding of compounds <b>2</b> and <b>3</b> have been investigated by theoretical methods for comparison

Comparison of Two Phosphinidenes Binding to Silicon(IV)dichloride as well as to Silylene

The cyclic alkyl­(amino) carbene (cAAC) anchored silylene with two phosphinidenes was isolated as (cAAC)­Si­{P­(cAAC)}₂ (<b>3</b>) at room temperature, which was synthesized from the reduction of (Cl₂)­Si­{P­(cAAC)}₂ (<b>2</b>) using 2 equiv of KC₈. Compound <b>2</b> resulted from the reaction of 2 equiv of (cAAC)­PK (<b>1</b>) with 1 equiv of SiCl₄. Compounds <b>2</b> and <b>3</b> are the first examples where two terminal phosphinidenes are binding each to a silicon center characterized by single crystal X-ray structural analysis. Furthermore, the structure and bonding of compounds <b>2</b> and <b>3</b> have been investigated by theoretical methods for comparison