Synthesis and crystal structure of bis(2,2′-bipyridyl)mononitritozinc(II) perchlorate. An example of a six-coordinate cis-octahedral ZnN4O2 chromophore

The crystal structure of bis(2,2-bipyridyl)mononitritozinc(II) perchlorate, [Zn(bipy)₂ (ONO)][ClO₄] (1) has been determined. The complex is monoclinic, with a = 10.9195(4) Å, b = 12.2320(5) Å, c = 16.5477(8) Å, = 105.6150(10), P2₁/n space group, with final R1 = 0.0657 and wR2 = 0.1630. The complex involves a [Zn(bipy)₂ (ONO)]⁺ cation and a [ClO₄]^– anion. The ZnN₄O₂ chromophore is six-coordinate, with a cis-distortion of the two oxygens of the nitrite, O(1) and O(2), at distances 2.216(5) and 2.197(5) Å from the zinc (Zn– O _mean = 2.206(5) Å, O = 0.019(5) Å) and two out of plane Zn–N bonds, Zn–N(2) and Zn–N(3), at 2.129(4) and 2.135(4) Å (Zn–n _mean/out = 2.132(4) Å, n _2,3 = 0.006(4) Å). The two inplane nitrogens, N(1) and N(4), at distances Zn–N(1) = 2.090(4) and Zn–N(4) = 2.085(4) Å (Zn–n _mean/in = 2.087(4) Å, n _1,4 = 0.005(4) Å) are greater than 2.0 Å, but slightly shorter than the axial bonds. The inplane angles ₁, ₂, and ₃ in 1 have values 150.33(18), 108.98(17), and 99.73(18) respectively. The stereochemistry is cis-distorted octahedral, with an ₃ = 99.37(18), which is lower than ₃ = 103.4(1) observed in [Zn(bipy)₂(ONO)][NO₃] (5). Comparison with the corresponding [Cu(bipy)₂(ONO)][Y] complexes suggested that the cis-distortion of the CuN₄O₂ chromophore in the copper(II) series does not originate in the Jahn–Teller or pseudo-Jahn–Teller effect.     

pH-Controlled Supramolecular Self-Assembly of Naphthalenediimide Appended l-Alanine and Ethylenediamine Asymmetric Bolaamphiphile

Design, synthesis and characterization of novel (2S)-2-[7-(2-aminoethyl)-1,3,6,8-tetraoxo-3,6,7,8-tetrahydrobenzo[lmn][3,8]phenanthrolin-2(1H)-yl]propanoic acid ( 1 ) bolaamphiphile, which combine naphthalene diimide (NDI) appended with l -alanine at one end of imide and ethylenediamine at the other end. An l -alanine bearing NDI-based asymmetric bolaamphiphile self-assembled at various pH ranging from 2 to 10 forms a variety of supramolecular nanostructures. The UV-Vis and emission spectroscopic techniques employed for the optical and photophysical properties study of bolaamphiphile 1 at various pH values. It was revealed that the change in pH alters both the optical and photophysical properties of bolaamphiphile 1 . Theoretical calculations used to investigate the electronic properties of the bolaamphiphile 1 . Dynamic light scattering experiments displayed formation of aggregates in solution and scanning electron microscopy (SEM) was used to visualize the nanostructures formed on silicon wafers. Furthermore, the X-ray diffraction was used to determine the nanostructure's packing properties i. e. crystalline/amorphous. Experimental circular dichroism (CD) spectroscopy results inferred and revealed the induction of chirality into the supramolecular systems, which was shown to be pH dependent. This study clearly demonstrates the manipulation of pH can control/tune chiral supramolecular structures and provide future methods for the development of chiral recognition and catalysis study.     

Comparative sedimentation and electrophoresis studies for zeta-potential measurement

Summary Very little literature exists regarding comparability of -potential values of identical systems computed by means of more than one of the four known categories of methods. Of the four methods, two, viz. sedimentation potential (SP) and electrophoretic mobility (EM) methods involve migration of solid particles immersed in liquid medium under force fields, and hence merit comparative investigation. The procedure for measurement of sedimentation potential outlined byQuist andWashburn (8) has been modified and improved upon. SP and _EM values for spherical glass particles as well as non-spherical rutile particles immersed in KCl and BaC₂ solutions in different concentrations show discrepancies of the order of ±20 percent. This exceeds cumulative reproducibility error, and may be due to (i) imperfection in theory (ii) surface conductivity effect and (iii) difference in hydrodynamic boundary layer thickness values.

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Zusammenfassung Die Arbeit befaßt sich mit dem Vergleich der -Potentialbestimmung mit 4 verschiedenen Methoden. Die Bestimmung des Sedimentationspotentials nachQuist undWashburn wurde modifiziert und verbessert. Als System wurden sphärische Glaspartikel und nichtkugelige Rutilpartikel in KCl- und BaCl₂-Lösungen verwendet. Differenzen bis zu 20% traten auf. Als Ursache werden i) Unvollständigkeit der Theorie ii) Oberflächenleitfähigkeit und iii) Unterschiede in der Dicke der hydrodynamischen Grenzschicht diskutiert.

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With 5 figures and 2 tables     

Structural systematics of the [Cu(chelate)3][Y]2 series. An interesting crystallographic structural insight involving vibronic coupling and the Jahn-Teller effect (JTE). The syntheses and low temperature crystal structures of tris(2,2'bipyridyl)copper(II) tetraphenylborate and tris(2,2'bipyridyl)zinc(II) tetraphenylborate

The crystal structures of [Cu(bipy)(3)][BPh(4)](2), 1, and [Zn(bipy)(3)][BPh(4)](2), have been determined at low temperature. 1 and 2 are closely related, but are not isostructural. Both contain a two-dimensional supramolecular construct (SC) involving a sandwich structure. 1 has a six-coordinate CuN(6) chromophore with a regular elongated octahedral stereochemistry and rhombic in-plane bond lengths. The associated tetragonality value, T, of 1 is 0.8868. 2 involves a six-coordinate octahedral chromophore. Differences between 1 and 2 relate to the tendency of copper(II) complexes to undergo a Jahn-Teller (JT) distortion. The zinc(II) cation feels solely the host site strain, whereas the copper(II) cation also involves vibronic JT type coupling. The copper polyhedron geometry is characterized by both phenomena, with the vibronic interaction dominating. Scatter plot analysis involving the tris-chelate copper(II) series suggests that neither pure Q(theta) or Q(epsilon) components or the a(2u) mode operate in isolation over the entire series. All three operate in combination with varying quantifiable contributions, leading to distortion from the regular tetragonal octahedral stereochemistry.     

Term structure of 4d-electron configurations and calculated spectrum in Sn-isonuclear sequence

Theoretical calculations of term structure are carried out for the ground configurations 4d^w, of atomic ions in the Sn isonuclear sequence. Atomic computations are performed to give a detailed account of the transitions in Sn⁺⁶ to Sn⁺¹³ ions. The spectrum is calculated for the most important excited configurations 4p⁵ 4dⁿ⁺¹, 4dⁿ⁻¹ 4f¹, and 4dⁿ⁻¹ 5p¹ with respect to the ground configuration 4dⁿ, with n=8-1, respectively. The importance of 4p-4d, 4d-4f, and 4d-5p transitions is stressed, as well as the need for the configuration-interaction CI treatment of the Δn=0 transitions. In the region of importance for extreme ultraviolet (EUV) lithography around 13.4 nm, the strongest lines were expected to be 4dⁿ-4p⁵ 4dⁿ⁺¹ and 4dⁿ-4dⁿ⁻¹ 4f¹.     

Demonstration of Allium sativum Extract Inhibitory Effect on Biodeteriogenic Microbial Strain Growth,Biofilm Development,and Enzymatic and Organic Acid Production

To the best of our knowledge, this is the first study demonstrating the efficiency of Allium sativum hydro-alcoholic extract (ASE) againstFigure growth, biofilm development, and soluble factor production of more than 200 biodeteriogenic microbial strains isolated from cultural heritage objects and buildings. The plant extract composition and antioxidant activities were determined spectrophotometrically and by HPLC–MS. The bioevaluation consisted of the qualitative (adapted diffusion method) and the quantitative evaluation of the inhibitory effect on planktonic growth (microdilution method), biofilm formation (violet crystal microtiter method), and production of microbial enzymes and organic acids. The garlic extract efficiency was correlated with microbial strain taxonomy and isolation source (the fungal strains isolated from paintings and paper and bacteria from wood, paper, and textiles were the most susceptible). The garlic extract contained thiosulfinate (307.66 ± 0.043 µM/g), flavonoids (64.33 ± 7.69 µg QE/g), and polyphenols (0.95 ± 0.011 mg GAE/g) as major compounds and demonstrated the highest efficiency against the Aspergillus versicolor (MIC 3.12–6.25 mg/mL), A. ochraceus (MIC: 3.12 mg/mL), Penicillium expansum (MIC 6.25–12.5 mg/mL), and A. niger (MIC 3.12–50 mg/mL) strains. The extract inhibited the adherence capacity (IIBG% 95.08–44.62%) and the production of cellulase, organic acids, and esterase. This eco-friendly solution shows promising potential for the conservation and safeguarding of tangible cultural heritage, successfully combating the biodeteriogenic microorganisms without undesirable side effects for the natural ecosystems.     

The Synthesis,Infra-Red Spectrum,Room Temperature Crystal Structure and Hydrogen Bonding Network of Bis(2,2′-Bipyridyl)Monobenzoatocopper(II) Nitrate Hydrate. Investigation into the Role of Benzoato Coordination in the Vibronic Coupling Interpretation of Static Copper(II) Complexes

The crystal structure of bis(2,2-bipyridyl)monobenzoatocopper(II) nitrate hydrate, [Cu(bipy)₂(O₂CPh)][NO₃]· H₂O, (1) has been determined. The [Cu(bipy)₂(O₂CPh)]⁺ cation chromophore is basically five-coordinate, but with O(1), the second oxygen atom of the benzoato ligand, occupying the sixth coordinate position at a distance 2.696(2)Å, from the copper. This suggests a (4 + 1 + 1^*) coordination, involving a distorted stereochemistry, with a CuN₄OO chromophore. O(2) is located at a distance 2.009(2)Å from the copper. The two oxygens, O(1) and O(2), therefore occupy cis positions of the distorted octahedral coordination sphere and the coordinated benzoate is a highly asymmetric, bidentate ligand with O = 0.687(2)Å and Cu—O_MEAN= 2.353(2)Å. The two nitrogens, N(1) and N(3), located in positions trans to the oxygen sites, at distances Cu—N(1)= 2.148(2)Å and Cu—N(3)= 2.058(2)Å[Cu—N_mean/in= 2.103(2)Å, N_1,3= 0.090(2)Å] are slightly longer than the bonds to the two mutually trans related 'axial' nitrogens, Cu—N(2)= 1.987(2)Å and Cu—N(4)= 1.977(2)Å. The 'equatorial' angles ₁, ₂ and ₃ have values 147.34(8), 93.29(9) and 105.39(9) respectively. The back-angle, ₃, of 105.39(9)° is unique for a bipy complex, containing a carbonyl-containing oxoanion in such series. The asymmetric nature of the benzoato ligand is further evidence of the static nature of such complexes. The complex also involves a hydrogen bonding network, linking the O(6) of the nitrate to H(2)W of the water molecule at a distance 2.052(6)Å and H(1)W to the long-bonded O(1) of the benzoato ligand, at a distance of 1.804(12)Å.