Micro-TLC Approach for Fast Screening of Environmental Samples Derived from Surface and Sewage Waters

In this work we demonstrated analytical capability of micro-planar (micro-TLC) technique comprising one and two-dimensional (2D) separation modes to generate fingerprints of environmental samples originated from sewage and ecosystems waters. We showed that elaborated separation and detection protocols are complementary to previously invented HPLC method based on temperature-dependent inclusion chromatography and UV-DAD detection. Presented 1D and 2D micro-TLC chromatograms of SPE (solid-phase extraction) extracts were optimized for fast and low-cost screening of water samples collected from lakes and rivers located in the area of Middle Pomerania in northern part of Poland. Moreover, we studied highly organic compounds loaded in the treated and untreated sewage waters obtained from municipal wastewater treatment plant “Jamno” near Koszalin City (Poland). Analyzed environmental samples contained number of substances characterized by polarity range from estetrol to progesterone as well as chlorophyll-related dyes previously isolated and pre-purified by simple SPE protocol involving C18 cartridges. Optimization of micro-TLC separation and quantification protocols of such samples were discussed from the practical point of view using simple separation efficiency criteria including total peaks number, log(product ΔhR _F), signal intensity and peak asymmetry. Outcomes of the presented analytical approach, especially using detection involving direct fluorescence (UV366/Vis) and phosphomolybdic acid (PMA) visualization are compared with UV-DAD HPLC-generated data reported previously. Chemometric investigation based on principal components analysis revealed that SPE extracts separated by micro-TLC and detected under fluorescence and PMA visualization modes can be used for robust sample fingerprinting even after long-term storage of the extracts (up to 4 years) at subambient temperature (?20 °C). Such approach allows characterization of wide range of sample components that are present in given extract in high and middle concentration range. Due to protocol simplicity and low cost of analysis this method can be useful for preliminary sample screening.     

Herbicidal ionic liquid with dual-function

Herbicidal ionic liquid with dual functions has been synthesized and characterized (properties, chemical stability and biological activity). 2-Chloroethyltrimethylammonium (4-chloro-2-methylphenoxy)acetate prepared in an alkaline environment undergoes the reaction of dehydrochlorination by the E2 mechanism. This may be described as a specific instance of providing third generation ILs with high potential of application, which preserve both pesticidal properties: the herbicidal activity due to their anions and plant growth inhibition effect due to their cations.     

Synthesis and Structure of 2‐Hydroxy‐2‐Methyl‐1,3‐Bis‐(Methyl 3′,4′,6′‐Tri‐O‐Acetyl‐β‐D‐Glucopyranosid‐2‐yl)‐Imidazolidine‐4,5‐Dione

The title compound was synthesized starting from methyl 3,4,6‐tri‐O‐acetyl‐2‐acetamido‐2‐deoxy‐β‐D‐glucopyranoside, oxalyl chloride, and methyl 3,4,6‐tri‐O‐acetyl‐2‐amino‐2‐deoxy‐β‐D‐glucopyranoside. The crystal and molecular structure of the obtained imidazolidine‐4,5‐dione have been determined by X‐ray analysis as well as ¹H and ¹³C NMR spectroscopy.     

Callitriche cophocarpa — a new rich source of active phenolic compounds

This study was focused on the analysis of the contents (by HPLC-DAD) and antioxidant activity of phenolic compounds of aquatic higher plant Callitriche cophocarpa. The novelty of the work was: 1) the study of the species which is almost unknown in the context of investigations of bio-active compounds and, 2) the application of a unique L-band electron resonance spectroscopy (L-band EPR) to measure antioxidant activity of samples. The results were compared with those obtained for microalgae Chlorella and Spirulina which are widely distributed as the diet supplements. The obtained results are very promising with respect to the freeze-dried material of Callitriche, which revealed both high level of phenolic compounds (33 mg g^?1 dry weight) and antioxidant activity (0.14 g of reduced DPPH· g^?1 dry weight). An isoform of sinapic acid appeared to be the main fraction in this sample. The average content of the total phenolic compounds in Callitriche freeze-dried samples was ca. 43 or 25 times higher than in the case of the Chlorella or Spirulina samples, respectively. These samples showed also 16 times lower scavenging activity in relation to freeze-dried Callitriche material.      

Three-dimensional through-bond homonuclear-heteronuclear correlation experiments for quadrupolar nuclei in solid-state NMR applied to (27)Al-O-(31)P-O-(27)Al networks

We present here the first 3D homonuclear/heteronuclear correlation experiment applied to quadrupolar nuclei and making use of the sole scalar J-coupling. This experiment, based on the 2D-Homonuclear-Heteronuclear Single Quantum Correlation (H-HSQC) experiment, uses a relayed transfer from the (27)Al central transition to neighbouring (31)P spins and to the central transition of a second (27)Al. It confirms the correlation map characterizing the two (27)Al and the (31)P NMR signatures of (27)Al-O-(31)P-O-(27)Al chemically bonded molecular motifs.     

Fundamental Characterization,Photophysics and Photocatalysis of a Base Metal Iron(II)-Cobalt(III) Dyad

A new base metal iron-cobalt dyad has been obtained by connection between a heteroleptic tetra-NHC iron(II) photosensitizer combining a 2,6-bis[3-(2,6-diisopropylphenyl)imidazol-2-ylidene]pyridine with 2,6-bis(3-methyl-imidazol-2-ylidene)-4,4′-bipyridine ligand, and a cobaloxime catalyst. This novel iron(II)-cobalt(III) assembly has been extensively characterized by ground- and excited-state methods like X-ray crystallography, X-ray absorption spectroscopy, (spectro-)electrochemistry, and steady-state and time-resolved optical absorption spectroscopy, with a particular focus on the stability of the molecular assembly in solution and determination of the excited-state landscape. NMR and UV/Vis spectroscopy reveal dissociation of the dyad in acetonitrile at concentrations below 1 mM and high photostability. Transient absorption spectroscopy after excitation into the metal-to-ligand charge transfer absorption band suggests a relaxation cascade originating from hot singlet and triplet MLCT states, leading to the population of the ³MLCT state that exhibits the longest lifetime. Finally, decay into the ground state involves a ³MC state. Attachment of cobaloxime to the iron photosensitizer increases the ³MLCT lifetime at the iron centre. Together with the directing effect of the linker, this potentially makes the dyad more active in photocatalytic proton reduction experiments than the analogous two-component system, consisting of the iron photosensitizer and Co(dmgH)₂(py)Cl. This work thus sheds new light on the functionality of base metal dyads, which are important for more efficient and sustainable future proton reduction systems.     

Gyroscope‐Like Molecules Consisting of PdX2/PtX2 Rotators within Three‐Spoke Dibridgehead Diphosphine Stators: Syntheses,Substitution Reactions,Structures, and Dynamic Properties

Threefold intramolecular ring‐closing metatheses of trans‐[MCl₂(P{(CH₂)_mCH?CH₂}₃)₂] are effected with Grubbs’ catalyst. Following hydrogenation catalyzed by [RhCl(PPh₃)₃], the title complexes trans‐[MCl₂(P((CH₂)_n)₃P )] (n=2m+2; M/n=Pt/14, 4 c ; Pt/16, 4 d ; Pt/18, 4 e ; Pd/14, 5 c ; Pd/18, 5 e ) and sometimes isomers partly derived from intraligand metathesis, trans‐[MCl₂{P(CH₂)_n(CH₂)_n}P (CH₂)_n)] ( 4′c–e , 5′e ), are isolated. These react with LiBr, NaI, and KCN to give the corresponding MBr₂, MI₂, and M(CN)₂ species (58–99 %). ¹³C NMR data show that the MX₂ moieties rapidly rotate within the diphosphine cage on the NMR timescale, even at ?120 °C. The reaction of 4 c and KSCN gives separable Pt(NCS)₂ and Pt(NCS)(SCN) adducts ( 13 c , 28 %; 14 c , 20 %), and those of 4 c , e and Ph₂Zn give PtPh₂ species ( 15 c , 61 %; 15 e , 90 %). ¹³C NMR spectra of 13 c – 15 c show two sets of CH₂ signals (ca. 2:1 intensity ratios), indicating that MX₂ rotation is no longer rapid. Reactions of 4 c or 4′c and excess NaC?CH afford the free diphosphines P{(CH₂)₁₄}₃P (91 %) and (CH₂)₁₄P (CH₂)₁₄P(C H₂)₁₄ (90 %). The latter has been crystallographically characterized as a bis(BH₃) adduct. The crystal structures of eight complexes with P(CH₂)₁₄P linkages (PtCl₂, PtBr₂, PtI₂, Pt(NCS)₂, PtPh₂, PdCl₂, PdBr₂, PdI₂) and 15 e have been determined, and intramolecular distances analyzed with respect to MX₂ rotation. The conformations of the (CH₂)₁₄ moieties and features of the crystal lattices are also discussed.     

Dynamic Formation of Hybrid Peptidic Capsules by Chiral Self‐Sorting and Self‐Assembly

Owing to their versatility and biocompatibility, peptide‐based self‐assembled structures constitute valuable targets for complex functional designs. It is now shown that artificial capsules based on β‐barrel binding motifs can be obtained by means of dynamic covalent chemistry (DCC) and self‐assembly. Short peptides (up to tetrapeptides) are reversibly attached to resorcinarene scaffolds. Peptidic capsules are thus selectively formed in either a heterochiral or a homochiral way by simultaneous and spontaneous processes, involving chiral sorting, tautomerization, diastereoselective induction of inherent chirality, and chiral self‐assembly. Self‐assembly is shown to direct the regioselectivity of reversible chemical reactions. It is also responsible for shifting the tautomeric equilibrium for one of the homochiral capsules. Two different tautomers (keto‐enamine hemisphere and enol‐imine hemisphere) are observed in this capsule, allowing the structure to adapt for self‐assembly.