Ladder polymers

Overberger, C. G.; Moore, James A.

doi:10.1007/bfb0051110

Cited by 77 publications

(19 citation statements)

References 86 publications

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“…A defining characteristic of ladder polymers is that their backbones consist of fused rings . In the absence of free bond rotations in the backbone, shape‐persistent ladder polymers possess extremely rigid conformations, giving rise to many interesting properties.…”

Section: Introductionmentioning

confidence: 99%

“…In the absence of free bond rotations in the backbone, shape‐persistent ladder polymers possess extremely rigid conformations, giving rise to many interesting properties. Rigid ladder polymers are also notoriously insoluble . A class of soluble ladder polymers, termed polymers of intrinsic microporosity (PIMs), developed by McKeown and coworkers have attracted significant attention recently .…”

Section: Introductionmentioning

confidence: 99%

“…Rigid ladder polymers are also notoriously insoluble. [1][2][3] A class of soluble ladder polymers, termed polymers of intrinsic microporosity (PIMs), developed by McKeown and coworkers have attracted significant attention recently. [4][5][6] The rigid and contorted backbones of PIMs prevent chain collapsing and close chain packing upon drying, resulting in solubility in organic solvents and high microporosity in the solid state.…”

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confidence: 99%

“…P2 0.5 mmol (207 mg) of 2, 0.01 mmol (2.2 mg) of Pd(OAc) 2 , 0.02 mmol (5.2 mg) of PPh 3 , 0.5 mmol (51 lL) of NBD, 1 mmol (326 mg) of Cs 2 CO 3 , and 1 mL of toluene were used. P2 was isolated as an off-white solid (118 mg, 69%)1 H NMR (400 MHz, CDCl 3 , d): 6.66 (s, 2H; Ar H), 3.25 (s, 4H; CH), 2.54-2.40 (m, 2H; CH), 2.17-2.13 (m, 6H; CH 3 ), 0.94 (s, 2H; CH 2 ).P(1-co-2) m/n 5 4/1 0.36 mmol (95 mg) of 1, 0.09 mmol (37.4 mg) of 2, 0.009 mmol (2.0 mg) of Pd(OAc) 2 , 0.018 mmol (4.7 mg) of PPh 3 , 0.45 mmol (46 lL) of NBD, 0.9 mmol (293 mg) of Cs 2 CO 3 , and 0.9 mL of toluene were used. P(1-co-2) was isolated as an off-white solid (83 mg, 97%).…”

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confidence: 99%

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Norbornyl benzocyclobutene ladder polymers: Conformation and microporosity

Lai

Liu

Xia

2017

J. Polym. Sci. Part A: Polym. Chem.

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Shape-persistent contorted ladder polymers are an intriguing and unusual class of polymers. Using catalytic arene-norbornene annulation (CANAL) polymerization and with norbornadiene and dibromoarenes as monomers, we synthesized a series of ladder polymers with fused norbornyl benzocyclobutene backbones and varied conformations. A diaryl spiro-orthocarbonate monomer was used to reorient the ladder backbone perpendicularly to induce three-dimensional kinks, and a p-dibromo-xylene comonomer was used to statistically vary the distance between the spirocyclic kinks in the ladder backbone. Norbornyl benzocyclobutene ladder polymers with no spirocyclic backbone twists possess much more compact conformations than ladder polymers with frequent spirocyclic backbone twists in solution. While spirocyclic twists in the polymer backbone had minor effects on the surface area and microporosity, incorporation of rotatable single bonds in the repeat unit significantly decreased both the surface area and pore volume.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Norbornyl benzocyclobutene ladder polymers: Conformation and microporosity

Lai

Liu

Xia

2017

J. Polym. Sci. Part A: Polym. Chem.

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“…Ladder polysilanes -(Si 2 R 2 ) n -were theoretical studied using density functional theory. 32 In order to compare the MgNiGe structure with the forthcoming AeNiGe structures we emphasize in Figure 1b Table 4). Table 4).…”

Section: Resultsmentioning

confidence: 99%

From One to Three Dimensions: Corrugated _∞¹[NiGe] Ribbons as a Building Block in Alkaline Earth Metal Ae/Ni/Ge Phases with Crystal Structure and Chemical Bonding in AeNiGe (Ae = Mg, Sr, Ba)

2013

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The new equiatomic nickel germanides MgNiGe, SrNiGe, and BaNiGe have been synthesized from the elements in sealed tantalum tubes using a high-frequency furnace. The compounds were investigated by X-ray diffraction both on powders and single crystals. MgNiGe crystallizes with TiNiSi-type structure, space group Pnma, Z = 4, a = 6.4742(2) Å, b = 4.0716(1) Å, c = 6.9426(2) Å, wR2 = 0.033, 305 F(2) values, 20 variable parameters. SrNiGe and BaNiGe are isotypic and crystallize with anti-SnFCl-type structure (Z = 4, Pnma) with a = 5.727(1) Å, b = 4.174(1) Å, c = 11.400(3) Å, wR2 = 0.078, 354 F(2) values, 20 variable parameters for SrNiGe, and a = 5.969(4) Å, b = 4.195(1) Å, c = 11.993(5) Å, wR2 = 0.048, 393 F(2) values, 20 variable parameters for BaNiGe. The increase of the cation size leads to a reduction of the dimensionality of the [NiGe] polyanions. In the MgNiGe structure the nickel and germanium atoms build a ∞(3)[NiGe] network with magnesium atoms in the channels. In SrNiGe and BaNiGe the ∞(1)[NiGe] ribbons are separated by strontium/barium atoms, whereas in the known CaNiGe structure the ribbons are fused to two-dimmensional atom slabs. The crystal chemistry and chemical bonding in AeNiGe (Ae = Mg, Ca, Sr, Ba) are discussed. The experimental results are reconciled with electronic structure calculations performed using the tight-binding linear muffin-tin orbital (TB-LMTO-ASA) method.

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