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Taking advantage of the conformational flexibility of the bpp ligand and aliphatic dicarboxylic acids, six interesting entangled coordination polymers, {[Cd(fum)(bpp)(H2O)]·(H2O)}n (1), {[Cd(fum)(bpp)2]·(H2O)5}n (2), {[Cd2(suc)1.5(bpp)2(NO3)(H2O)2]·6H2O}n (3), {[Cd(suc)(bpp)2]·(H2O)1.5}n (4), {[Cd2(glu)2(bpp)3]·10H2O}n (5), and {Cd(adp)(bpp)(H2O)}n (6) have been prepared and structurally characterized (bpp = 1,3-bi(4-pyridyl)propane, fum = fumaric, suc = succinate, glu = glutaric, adp = adipic). Compounds 1 and 2 are comprised of undulated 2D 44-sql networks. In the structure of compound 1, two identical undulated layers are parallelly interpenetrated with each other to give a 2D → 2D interpenetrating framework. For 2, the dangling arms projected from 2D layers are intercalated into the neighboring sheets, producing a 2D → 3D polythreading framework. Compound 3 shows a rare example of a 2D self-penetrating framework with a (3,4)-connected (42·63·8)(42·6) topology. Compound 4 presents an unusual 2D self-threading network with a novel 4-connected {42·63·8} topology. Compound 5 displays a 3D self-penetrating system based on a 2D → 3D parallel polycatenation array. Compound 6 exhibits an unprecedented 3D self-penetrating structure having both 1D + 1D → 1D polycatenation and 3D + 3D → 3D interpenetration characteristics. A comparison of these six compounds demonstrates that both the different spacer lengths of the aliphatic dicarboxylates and reactant ratios appear to play a significant role in the assembly of entangled frameworks. In addition, thermal stabilities and photoluminescence properties of 1–6 have been examined in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

A series of Zn/Cd(ii) coordination polymers, namely, [Zn(IDPA)(H2O)]n·n(H2O) (1), [Cd(IDPA)(bpp)]n·n(H2O) (2), [Cd(IDPA)(4,4′-bpy)1/2]n (3), [Zn(IDPA)(4,4′-bpy)1/2]n (4), [Zn4(IDPA)4(phen)2·(H2O)2]n·2n(H2O) (5), [Zn(IDPA)(phen)·(H2O)]n·n(H2O) (6) and [Zn(IDPA)(2,2′-bpy)·(H2O)]n·n(H2O) (7), have been prepared on the basis of a bulky 1,3-benzenedicarboxylate derivative ligand, 5-(1-oxoisoindolin-2-yl)isophthalic acid (H2IDPA), with the help of 1,3-bis(4-pyridyl)propane (bpp), 4,4′-bipyridine (4,4′-bpy), 1,10-phenanthroline (phen) or 2,2′-bipyridine (2,2′-bpy) as a secondary ligand. H2IDPA is a luminous ligand with a large rigid π-conjugated system, and the solid-state luminescence properties of compounds 1–7 have been comparatively investigated. The results indicate that their luminescence properties have been enhanced compared to those of the free ligand, especially for compounds 2–7 which have been further regulated by N-donor ligands with a π-conjugated system. Compound 2 is a 2D layer structure, and its quantum yield (QY) is 39.80%, which is much higher than those of the H2IDPA ligand (QY = 4.41%) and compound 1 (QY = 6.32%). From the viewpoint of crystal structure diversity and comparison, our results further demonstrate that ligands with a large π-conjugated system have a promotional effect on luminescence properties of coordination polymers. [ABSTRACT FROM AUTHOR]

In a double-well system, we investigate theoretically the population distribution of a particle perturbed by a weak sinusoidal signal with a Gaussian white noise accompanied. Our numerical simulation shows that the probability of the particle staying in the right potential well, PR, exhibits an extreme value at specific noise intensity D depending on the frequency of the sinusoidal signal, which is a key feature of stochastic resonance. This is confirmed by calculating the power spectrum of the output signal, in which the extreme value of the amplitude locates at the same noise intensity. These results provide us with a new way to quantify the stochastic resonance by measuring the population distribution of the particle. [ABSTRACT FROM AUTHOR]

We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current. [ABSTRACT FROM AUTHOR]

A tunable superconducting half-wavelength coplanar waveguide resonator (CPWR) with Nb parallel nanowires ∼ 300 nm in width embedded in the center conductor was designed, fabricated, and measured. The frequency shift and the amplitude attenuation of the resonance peak under irradiation of 404-nm pulse laser were observed with different light powers at 4.2 K. The RF power supplied to such a CPWR can serve as current bias, which will affect the light response of the resonator. [ABSTRACT FROM AUTHOR]