Facile Strategy for Preparing a Rosin-Based Low‑<i>k</i> Material: Molecular Design of Free Volume

Low-k dielectrics are urgently needed in modern integrated circuits. The introduction of free volume instead of porous structures has become a powerful strategy to reduce the k value. According to this strategy, the biomass resource rosin-containing hydrogenated phenanthrene ring was introduced into benzocyclobutene (BCB) resin to reduce the k value; then a rosin-based BCB monomer was successfully synthesized. Meanwhile, the BCB monomer without a rosin skeleton was prepared. After converting the monomers into thermo-crosslinked materials, notably that the rosin skeleton has a great influence on the free volume and k value of the material. The fractional free volume and k value of the former are 26% and 2.44, respectively, and those of the latter are 14% and 2.84, respectively. In addition, the distances between molecular chains and the density of the former are 0.60 nm and 1.06 g cm–3, respectively; those of the latter are 0.56 nm and 1.28 g cm–3, respectively. These data show that introducing hydrogenated phenanthrene rings occupies part of the space and hinders the packing of molecular chains, which increases the distance between molecular chains and reduces the density of the polymer, resulting in an increasing free volume and a reducing k value. Notably that introducing hydrogenated phenanthrene rings cannot affect other properties of the material. Therefore, this research indicates that introducing rosin skeletons can prepare high-performance materials, which provide some promising low-k materials for the development of electronics and microelectronics

Rigidity versus Flexibility of Ligands in the Assembly of Entangled Coordination Polymers Based on Bi- and Tetra Carboxylates and N‑Donor Ligands

Seven Zn­(II) coordination polymers including [Zn­(pbda)­(<i>p</i>-bimb)]­·H₂O (<b>1</b>), [Zn­(pbda)­(bpa)_0.5] (<b>2</b>), [Zn­(pbda)­(bpp)] (<b>3</b>), [Zn­(Hpbda)₂­(bibm)₂] (<b>4</b>), [Zn­(pbta)_0.5­(m-bimb)]­·H₂O (<b>5</b>), [Zn­(pbta)_0.5­(bpp)­(H₂O)] (<b>6</b>), and [Zn­(H₂pbta)­(bibm)]­·H₂O (<b>7</b>) (H₂pbda = 4,4′-{[1,4-phenylenebis­(methylene)]­bis­(oxy)}­dibenzoic acid; p-bimb = 1,4-bis­(1<i>H</i>-imidazol-l-yl)­methyl)­benzene; bpa = 1,2-bis­(4-pyridyl)­ethane; bpp = 1,3-bis­(4-pyridyl)-propane; bibm = 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl; m-bimb = 1,3-bis­(1<i>H</i>-imidazol-l-yl)­methyl)-benzene; H₄pbta = 5,5′-phenylenebis­(methylene)-1,1′-3,3′-(benzene-tetracarboxylic acid) were prepared under solvothermal conditions and structurally characterized. Compound <b>1</b> shows a three-dimensional (3D) channel-like architecture constructed by helical chain subunits. Compound <b>2</b> shows a rare 2D + 2D + 2D → 2D network with both polyrotaxane and polycatenane features. <b>3</b> holds a 2D layer structure constituted of metal-sharing right- and left-handed helical chains. Compound <b>4</b> presents a one-dimensional (1D) chain which is decorated by long side arms around the chain. Compound <b>5</b> possesses a 2D wave-like layer formed by [Zn₂(<i>m</i>-bimb)]_<i>n</i> chains by linear pbta ligands. Compound <b>6</b> displays a 3D framework that is stabilized by hydrogen bonding interactions between the coordinated H₂O molecules and the neighboring carboxylate oxygen atoms. Compound <b>7</b> possesses a 1D + 1D → 2D polycatenation motif. The results demonstrated that the rigidity versus flexibility of the ligands along with the number of carboxyl groups make an impact on the structural diversities of the entangled coordination polymers. Moreover, compounds <b>3</b> and <b>6</b> as representative examples possessed high catalytic efficiency for the photodecomposition of methyl blue in water using natural sunlight irradiation

Construction of Entangled Coordination Polymers Based on M²⁺ Ions, 4,4′-{[1,2-Phenylenebis(methylene)]bis(oxy)}dibenzoate and Different N‑Donor Ligands

Reactions of several transition metal [M = Mn­(II), Cu­(II), Zn­(II), Co­(II)] salts with 4,4′-{[1,2-phenylenebis­(methylene)]­bis­(oxy)}­dibenzoic acid (H₂L) and auxiliary N-donor ligands afforded a series of entangled coordination frameworks, [Mn₂L₂(4,4′-bpy)₂]­[Mn₂L₂(H₂O)₂]·2H₂O <b>(1)</b>, [CuL­(bbm)]·0.5H₂O <b>(2)</b>, [CuL­(4,4′-bpy)_0.5] <b>(3)</b>, [Zn₃L₂(4,4′-bpy)₂(HCOO)₂] <b>(4)</b>, [ZnL­(4,4′-bpy)]₂·H₂O <b>(5)</b>, [Co₄L₄(bpp)₂]·DMF <b>(6)</b>, [Co₂L₂(bbm)]₂·2H₂O <b>(7)</b>, and [CoL­(2,2′-bpy)] <b>(8)</b> [2,2′-bpy = 2,2′-bipyridine; 4,4′-bpy = 4,4′-bipyridine; bbm =1,4-di­(1H-imidazol-1-yl)­benzene; bpp = 1,3-bis­(4-pyridyl)­propane]. Their structures were characterized by elemental analysis, IR spectra, and TG analysis and further determined by single-crystal X-ray diffraction analysis. Compound <b>1</b> has an uncommon 2D_layer + 1D_chain → 3D framework, while <b>2</b> displays a 2-fold interpenetrated 3D framework. Compounds <b>3</b>–<b>5</b> show different entangled networks though they adopt the same 4,4′-bpy as the auxiliary ligand. Compounds <b>3</b> and <b>5</b> show 2-fold interpenetrated 2D networks, showing both polycatenane and polyrotaxane characters. Compound <b>4</b> possesses a 2D → 3D polythreaded architecture. Compound <b>6</b> has a 3-fold interpenetrated 3D framework by using bpp as the second ligand. Compound <b>7</b> presents a 3D framework with a (4⁴·6²·8⁸·12)­(4⁴·6²)­(8) topology. Compound <b>8</b> presents a 1D helical chain constructed by linking [Co­(2,2′-bpy)]²⁺ units via L ligands. The results provided an interesting insight into how metal ions, auxiliary N-donor ligands, and molar ratios of the components exert great impact on the formation of these entangled networks. The thermal and luminescent properties of <b>1</b>–<b>8</b> in solid state at ambient temperature were also investigated

Coordination Polymer-Mediated Molecular Surgery for Precise Interconversion of Dicyclobutane Compounds

A Cd(II)-based coordination polymer {[Cd2(5-F-1,3-bpeb)2(FBA)4]·H2O}n (CP1) was obtained from Cd(II) salt, 5-fluoro-1,3-bis[2-(4-pyridyl)ethenyl]benzene (5-F-1,3-bpeb), and p-fluorobenzoic acid (HFBA). Within the one-dimensional chain structure of CP1, a pair of 5-F-1,3-bpeb was arranged in a face-to-face style. Upon UV irradiation and heat treatment, multiple cyclobutane isomers, including specific monocyclobutanes (1 with an endo-cyclobutane ring in CP1-1 and 1′ with an exo-cyclobutane ring in CP1-1′) and dicyclobutanes (endo,endo-dicyclobutane 2α in CP1-2α, exo,endo-dicyclobutane 2β in CP1-2β, and exo,exo-dicyclobutane 2γ in CP1-2γ) were stereoselectively produced. These isomers could be interconverted inside the CP via cutting/coupling specific bonds, which may be regarded as a type of molecular surgery. The precision of cutting/coupling relied on the thermal stability of the cyclobutanes and the alignment of the reactive alkene centers. The conversion processes were tracked through nuclear magnetic resonance, in situ powder X-ray diffraction, and IR spectroscopy. This approach can be considered as skeletal editing to construct complex organic compounds directly from one precursor

Five new cobalt(II) complexes based on indazole derivatives: synthesis, DNA binding and molecular docking study

Five cobalt(II) complexes based on 1H-indazole-3-carboxylic acid (H2L), [Co(phen)(HL)2]·2H2O (1), [Co(5,5′-dimethyl-2,2′-bipy)(HL)2] (2), [Co(2,2′-bipy)2(HL)2]·5H2O (3), [Co2(2,9-dimethyl-1,10-phen)2(L)2] (4) and [Co2(6,6′-dimethyl-2,2′-bipy)2(L)2]·H2O (5) (2,2'-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and structurally characterized by elemental analyses, IR and UV-vis spectroscopies and single-crystal X-ray crystallography. The results indicate that 1–3 possess mononuclear Co(II) structures, while 4 and 5 exhibit binuclear structure. 1D water tape which is linked by the multiple hydrogen bonds was embedded in the 3D motif of complex 3. Complexes 4 and 5 show two orthogonal planes of motif that was constituted by phen/2,2′-bipy and indazole acid, respectively. The intermolecular interactions including hydrogen bonding and π-π stacking interactions are stabilizing these complexes. The interactions of the synthesized complexes with calf-thymus DNA (CT-DNA) have been investigated by UV-vis absorption titration, ethidium bromide displacement assay and viscosity measurements. The results reveal that the complexes could interact with CT-DNA via a groove binding mode. Their behavior rationalization was further theoretically studied by molecular docking.</p

Construction of Entangled Coordination Polymers Based on M²⁺ Ions, 4,4′-{[1,2-Phenylenebis(methylene)]bis(oxy)}dibenzoate and Different N‑Donor Ligands

Reactions of several transition metal [M = Mn­(II), Cu­(II), Zn­(II), Co­(II)] salts with 4,4′-{[1,2-phenylenebis­(methylene)]­bis­(oxy)}­dibenzoic acid (H₂L) and auxiliary N-donor ligands afforded a series of entangled coordination frameworks, [Mn₂L₂(4,4′-bpy)₂]­[Mn₂L₂(H₂O)₂]·2H₂O <b>(1)</b>, [CuL­(bbm)]·0.5H₂O <b>(2)</b>, [CuL­(4,4′-bpy)_0.5] <b>(3)</b>, [Zn₃L₂(4,4′-bpy)₂(HCOO)₂] <b>(4)</b>, [ZnL­(4,4′-bpy)]₂·H₂O <b>(5)</b>, [Co₄L₄(bpp)₂]·DMF <b>(6)</b>, [Co₂L₂(bbm)]₂·2H₂O <b>(7)</b>, and [CoL­(2,2′-bpy)] <b>(8)</b> [2,2′-bpy = 2,2′-bipyridine; 4,4′-bpy = 4,4′-bipyridine; bbm =1,4-di­(1H-imidazol-1-yl)­benzene; bpp = 1,3-bis­(4-pyridyl)­propane]. Their structures were characterized by elemental analysis, IR spectra, and TG analysis and further determined by single-crystal X-ray diffraction analysis. Compound <b>1</b> has an uncommon 2D_layer + 1D_chain → 3D framework, while <b>2</b> displays a 2-fold interpenetrated 3D framework. Compounds <b>3</b>–<b>5</b> show different entangled networks though they adopt the same 4,4′-bpy as the auxiliary ligand. Compounds <b>3</b> and <b>5</b> show 2-fold interpenetrated 2D networks, showing both polycatenane and polyrotaxane characters. Compound <b>4</b> possesses a 2D → 3D polythreaded architecture. Compound <b>6</b> has a 3-fold interpenetrated 3D framework by using bpp as the second ligand. Compound <b>7</b> presents a 3D framework with a (4⁴·6²·8⁸·12)­(4⁴·6²)­(8) topology. Compound <b>8</b> presents a 1D helical chain constructed by linking [Co­(2,2′-bpy)]²⁺ units via L ligands. The results provided an interesting insight into how metal ions, auxiliary N-donor ligands, and molar ratios of the components exert great impact on the formation of these entangled networks. The thermal and luminescent properties of <b>1</b>–<b>8</b> in solid state at ambient temperature were also investigated