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To advance biomass-metal oxide composite synthesis, develop its interfacial chemistry and raise its performance in applications, specifying local structures and their effects are of great importance. Herein, a facile hydrothermal route was utilized to prepare a composite of renewable cellulose and zinc oxide. Microstructures from nanoscale to atomic level were examined with electron microscopy, spectroscopic technique and relativistic density functional theory. ZnO nanoparticles uniformly grow on linear cellulose nanofiber, affording an orderly hierarchical structure in general. Chemical interfacial coupling is computationally borne out. Three types of local structures with different hydrogen locations are energetically favored; notably the hydrogen-transfer one is most possibly occurring in the composite, whose interfacial interaction is dominated by orbital attractions and interfacial strength reaches − 5.06 eV. Electronic structures of the composite rationalized experimental diffuse reflectance spectra. The influence of different hydrogen positions in composite on various properties was discussed in detail. Experimental and computational characterizations unravel local structures of a typical cellulose–ZnO composite, which show different hydrogen positions. Hydrogen-transfer isomers are found the most possibly occurring, resembling the photoanode in dye-sensitized solar cells. The interfacial nature and interaction strength as well as electronic structures are determined by hydrogen locations.

Because biomass lignin shows good adsorption activity, its derivatives such as alkali lignin and kraft lignin have been applied in water treatment; however, sodium lignosulfonate (SLS), mainly limited by its high water solubility, is not applicable in this respect. In this work, we fabricated SiO2@SLS mesoporous adsorbent using a facile solution coating method by one step. SLS coating SiO2 enables the former to be “separated” from water, accomplishing the soluble to insoluble conversion. This change makes the composite more suitable and efficient to remove organic pollutants from water than the SLS precursor. It is found that interfacial hydrogen bonds play a significant role in the conversion, which is further corroborated by density functional theory calculations. Various characterizations show that SiO2@SLS is composed of uniform particles around 80 nm in size. Abundant mesopores with diameters ranging from 2 to 3 nm are found on the surface of SiO2@SLS nanoparticles. The specific surface areas of SiO2@SLS were measured between 293.4 and 33.2 m2 g−1, depending on the SLS amount used in the preparing process. Originating from the bio-adsorbent lignin precursor, the SiO2@SLS composite shows excellent adsorption property. Representatively, SiO2@SLS-0.6 is able to efficiently remove methylene blue (MB), almost twice as much as SiO2-0 does; its adsorption capacity (Qm) reaches 206.2 mg g−1 according to the Langmuir model fitting; notably, SiO2@SLS-0.6 works very well even in a high-concentration MB solution (50 mg L−1), showing removal efficiencies at 90.0% (within 1 h) and 99.9% (720 h, i.e., 30 days). Plus having remarkable adsorption stability, our composite SiO2@SLS is anticipated to be promising in application of polluted water treatment.

Relativistic density functional theory finds that two isomers of a diuranium(III) complex of a polypyrrolic macrocycle (H4L) feature active sites on uranium moieties, allowing for their potential application in activating industrially and economically important small molecules. To address this, a series of adducts [(X)nU2(L)]((2-m)+) (X = THF, I(-) and HI; n = 1 and 2; m = 0, 1 and 2) have been examined. The coordination from X to the exposed uranium(s) changes the general geometry and electronic structure slightly. Thermodynamic calculations reveal that iodine termination is energetically favored over THF/HI coordination. Graphical abstract Scalar and spin-orbit coupling relativistic DFT calculation reveals that the active sites on the uranium moieties of [U2(L)](2+) lead to formation of adducts [(THF)nU2(L)](2+), [InU2(L)]((2-n)+) and [(HI)nU2(L)](2+) (n = 1 and 2). Coordination to the exposed uranium(s) changes geometrical and electronic properties slightly, but iodine termination is the most energetically favored.

Eighteen actinyl complexes of a Schiff-base polypyrrolic macrocycle (H4L), [(Sol)(AnmO2)(H2L)]n− (Sol = Vacant, pyridine (py) and tetrahydrofuran (THF); An=U, Np and Pu; m = VI and n = 0, m = V and n = 1) were investigated using relativistic density functional theory. Comparison of complexes with and without the explicit solvent coordination to the metal center, and changes in actinide element and metal oxidation state provide insight into their effects on structural and energetic properties of the complexes. Compared with those of the solvent-free complexes, the An=O bond lengths of the solvated complexes differ within 0.01 A, and the deviation of the O=An=O angles is less than 1°. The H···Oendo bonds are relatively sensitive to the explicit solvent coordination, showing the largest discrepancy of 0.05 A. Charges and electron-spin densities of actinides are only slightly affected by the inclusion of the explicit solvent. Reduction potentials of actinyl complexes have been addressed, and their dependence on the bulk solvent polarity is being discussed, using a simple model based on the Born equation.

A series of ruthenium(II) complexes Ru(fppz)2(CO)L [fppz = 3-trifluoromethyl-5(2-pyridyl)pyrazole; L = pyridine (1), 4-dimethylaminopyridine (2), 4-cyanopyridine (3)] were designed and investigated theoretically to explore their electronic structures, absorption, and emissions as well as the solvatochromism. The singlet ground state and triplet excited state geometries were fully optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ level, respectively. The HOMO of 1–3 is composed of dyz(Ru) atom and π(fppz). The LUMO of 1 and 2 is dominantly contributed by π*(fppz) orbital, but that of 3 is contribute by π*(L). Absorption and phosphorescence in vacuo, C6H12, and CH3CN media were calculated using the TD-DFT level of theory with the PCM model based on the optimized ground and excited state geometries, respectively. The lowest-lying absorption of 1 and 2 at 387 and 391 nm is attributed to {[dyz(Ru) + π(fppz)] → [π*(fppz)]} transition, but that of 3 at 479 nm is assigned to {[dyz(Ru) + π(fppz)] → [π*(L)]} transition. The phosphorescence of 1 and 2 at 436 and 438 nm originates from 3{[dyz(Ru) + π(fppz)] [π*(fppz)]} excited state, while that of 3 at 606 nm is from 3{[dyz(Ru) + π(fppz)] [π*(L)]} excited state. The calculation results showed that the absorption and emission transition character can be changed from MLCT/ILCT to MLCT/LLCT transition by altering the substituent on the L ligand. The phosphorescence of 1 and 2 does not have solvatochromism, but that of 3 at 606 nm (vacuo), 584 nm (C6H12), and 541 nm (CH3CN) is strongly dependent on the solvent polarity, so introducing electron-withdrawing group on ligand L will induce remarkable solvatochromism.

Electronic structures, absorptions and emissions of a series of (ppy)2Ir(acac) derivatives (ppy = 2- phenylpyridine; acac = acetoylacetonate) with fluoro substituent on ppy ligands were investigated theoretically. The ground and excited states geometries were fully optimized at B3LYP/LANL2DZ and CIS/LANL2DZ level, respectively. The HOMO is composed of d(Ir) and π(C∧N), while the LUMO is localized on C∧N ligand. The absorptions and emissions in CH2Cl2 media were calculated under the TD–DFT level with PCM model. The lowest-lying absorption of these complexes is dominantly attributed to metal-to-ligand and intraligand charge transfer (MLCT/ILCT) transitions and the emission of them originates from 3MLCT/3ILCT excited states. The absorption and emission of these complexes are blue-shifted by increasing the number of fluoro on phenyl, but the spectra are red-shifted by adding fluoro on pyridyl. While a single fluoro of different substituted site on phenyl results in different extent blue-shift to the spectra.

We have studied the ground and excited states of the three dendritic polynuclear Pt(II) complexes 1-[Cl(PH3)2PtC≡ C]-3,5-[HC≡C]C6H3 (1), 1,3-[Cl(PH3)2PtC≡C]2-5-[HC≡C]C6H3 (2), and 1,3,5-[Cl(PH3)2-PtC≡C]3C6H3 (3), by using the B3LYP and UB3LYP methods, respectively. TDDFT approach with the PCM model was performed to predict the emission spectra properties of 1–3 in CH2Cl2 solution. We first predicted the excited-state geometries for the three complexes. With the change of the number of Pt(II) atom, 1–3 show the different geometry structures in both the ground and excited states; furthermore, the increase of the metal density from 1 to 3 results in the red shift of the lowest-energy emissions along the series. The luminescent properties of 1 are somewhat different from those of 2 and 3. The emission properties of 2 and 3 are richer than 1. Our conclusion can give a good support for designing the high efficient luminescent materials.

The Ru(II) sensitizers, [((HOOC) n -(Pc))Ru(NCS)2]2− (labeled as Pc-n; n = 0–4, Pc = phthalocyanine) and [((HOOC) n -(TBPor))Ru(NCS)2]2− (Por-n; n = 0–4, TBPor = tetrabenzoporphyrin), for solar cells have been studied on their optoelectronic and redox properties using density functional theory (DFT) and time-dependent DFT. It was shown that the number of carboxylic groups bonding to tetrapyrrolic ligands (i.e. Pc and TBP or) can fine-tune electronic structures and absorption transitions of Pc-n and Por-n, but slightly change their geometries. The tetrapyrrolic macrocycles, especially in the cases peripherally substituted by carboxylic acids, are the ideal spot to accommodate excited electrons. Analyses on both atomic electron-spin density and electronic structures reveal that one-electron oxidation of Pc-n and Por-n occurs around ruthenium and –NCS moieties; in contrast, that of [(Pc)Ru(Py-COOH)2] (PcRuPy, Py = pyridine) was calculated to be macrocycle-based, agreeing with experimental observation. Additionally, intensities of Q absorption bands of Pc-n and Por-n have been calculated to be strongly enhanced upon increasing the carboxylic acid number. Among them, Por-4 shows intense and broad Q bands centered at 508, 546, and 617 nm, matching well with solar spectrum. In brief, the present calculated results of electronic structures, spectral features, and oxidation potentials as well as comparison with experimentally known dyes of PcRuPy and [((HOOC)2-(bipyridine))2Ru(NCS)2] (N3) suggest that Pc-n and Por-n, especially Por-4, would be suitable photosensitizers for dye-sensitized solar cells (DSSCs).

Hierarchical ZnO nanoparticle-bar, nanomesh-lamina, and quasi-nanosphere structures have been successfully synthesized by the precipitation method with assistance of sodium lignosulphonate (SL). It is shown that the obtained ZnO nanomaterials are well crystallized and possess hexagonal wurtzite structure after calcination. Morphologies of ZnO with particle sizes ranging from 50 to 200 nm can be fabricated by tuning the SL amount in our synthetic route. Plenty of pores have been observed both in nanoparticle-bar and nanomesh-lamina ZnO. This may provide scaffold microenvironments to enhance their photocatalytic activity. It is evident that the synthesized ZnO exhibits good photocatalytic activity of degrading methylene blue, even under a very low-power UV illumination, which allows for the treatment of wastewater containing organic pollutants in an effective way. Among our synthesized nanomaterials, the nanomesh-lamina ZnO has the highest photodegradation efficiency, achieving nearly 100 % degradation only within 1.5 h (UV irradiation power of 12 W). As these ZnO nanomaterials are simply synthesized using SL which is a pulp industry by-product and their intrinsic hierarchical nanostructures show outstanding photocatalytic behavior, we expect the present controllable, environment-friendly, and cost-effective approach to be applied in the synthesis of small-sized ZnO materials.