Dielectric spectroscopy (DS) is an important technique for scientific and technological investigations in various areas. DS sensitivity and operating frequency ranges are critical for many ...applications, including lab-on-chip development where sample volumes are small with a wide range of dynamic processes to probe. In this work, we present the design and operation considerations of radio-frequency (RF) interferometers that are based on power-dividers (PDs) and quadrature-hybrids (QHs). Such interferometers are proposed to address the sensitivity and frequency tuning challenges of current DS techniques. Verified algorithms together with mathematical models are presented to quantify material properties from scattering parameters for three common transmission line sensing structures, i.e., coplanar waveguides (CPWs), conductor-backed CPWs, and microstrip lines. A high-sensitivity and stable QH-based interferometer is demonstrated by measuring glucose-water solution at a concentration level that is ten times lower than some recent RF sensors while our sample volume is ~ 1 nL. Composition analysis of ternary mixture solutions are also demonstrated with a PD-based interferometer. Further work is needed to address issues like system automation, model improvement at high frequencies, and interferometer scaling.
A polyterpyridinyl building block-based nutlike hexagonal bismetallo architecture with a central hollow Star of David was assembled by a stepwise strategy. This nanoarchitecture can be viewed as a ...recursive mathematical form that possesses a supramolecular corner-connected cyclic structure, i.e., a triangle or rhombus at various levels of scale or detail. The key metallo-organic ligand (MOL) with four uncomplexed free terpyridines was obtained by a final Suzuki cross-coupling reaction with a tetrabromoterpyridine Ru dimer. The molecular metallorhombus was prepared by reacting the MOL with a 60° bis-terpyridine and Fe2+. The giant hollow hexagonal nut with a diameter of more than 11 nm and a molecular weight of ca. 33 kDa was obtained in near-quantitative yield by mixing the two types of multi-terpyridine ligands with Fe2+. The supramolecular architecture was characterized by NMR (1H and 13C), 2D NMR (COSY and ROESY), and DOSY spectroscopies, high-resolution electrospray ionization mass spectrometry, traveling-wave ion mobility mass spectrometry, and transmission electron microscopy.
For the past three decades, the coordination-driven self-assembly of three-dimensional structures has undergone rapid progress; however, parallel efforts to create large discrete two-dimensional ...architectures-as opposed to polymers-have met with limited success. The synthesis of metallo-supramolecular systems with well-defined shapes and sizes in the range of 10-100 nm remains challenging. Here we report the construction of a series of giant supramolecular hexagonal grids, with diameters on the order of 20 nm and molecular weights greater than 65 kDa, through a combination of intra- and intermolecular metal-mediated self-assembly steps. The hexagonal intermediates and the resulting self-assembled grid architectures were imaged at submolecular resolution by scanning tunnelling microscopy. Characterization (including by scanning tunnelling spectroscopy) enabled the unambiguous atomic-scale determination of fourteen hexagonal grid isomers.
Spectrum matching is the most common method for compound identification in mass spectrometry (MS). However, some challenges limit its efficiency, including the coverage of spectral libraries, the ...accuracy, and the speed of matching. In this study, a million-scale in-silico EI-MS library is established. Furthermore, an ultra-fast and accurate spectrum matching (FastEI) method is proposed to substantially improve accuracy using Word2vec spectral embedding and boost the speed using the hierarchical navigable small-world graph (HNSW). It achieves 80.4% recall@10 accuracy (88.3% with 5 Da mass filter) with a speedup of two orders of magnitude compared with the weighted cosine similarity method (WCS). When FastEI is applied to identify the molecules beyond NIST 2017 library, it achieves 50% recall@1 accuracy. FastEI is packaged as a standalone and user-friendly software for common users with limited computational backgrounds. Overall, FastEI combined with a million-scale in-silico library facilitates compound identification as an accurate and ultra-fast tool.
Label-free measurement and analysis of single bacterial cells are essential for food safety monitoring and microbial disease diagnosis. We report a microwave flow cytometric sensor with a microstrip ...sensing device with reduced channel height for bacterial cell measurement.
B and
K-12 were measured with the sensor at frequencies between 500 MHz and 8 GHz. The results show microwave properties of
cells are frequency-dependent. A LightGBM model was developed to classify cell types at a high accuracy of 0.96 at 1 GHz. Thus, the sensor provides a promising label-free method to rapidly detect and differentiate bacterial cells. Nevertheless, the method needs to be further developed by comprehensively measuring different types of cells and demonstrating accurate cell classification with improved machine-learning techniques.
Coordination‐driven self‐assembly has led to the formation of various aesthetical polyhedrons and compounds with advanced functions. Whereas two‐dimensional supramolecules with complex and giant ...skeletons are plentiful, the constructions of polyhedrons are limited by using basic polygons as the panels. Herein, we report the modular synthesis of a tessellated triangle and tessellated octahedron with metal‐organic modules as the panels and formed via template‐driven self‐assembly. These architectures have diameters on the order of 10.9 nm and molecular weights greater than 84 kDa. Interestingly, fiber and spherical‐like nanostructures could be formed from the tessellated triangles and octahedrons, respectively, through hierarchical self‐assembly. In addition, after hybridization with carbon nanotubes, the supramolecules exhibit electrochemical reduction activity for CO2 to CO.
The self‐assembly of a tessellated triangle T1 and the construction of a tessellated octahedron O1 containing metal‐organic modules as the panels are demonstrated. O1 has a diameter on the order of 10.9 nm and a molecular weight greater than 84 kDa. After hybridization with carbon nanotubes, the supramolecules exhibit electrochemical reduction activity for CO2 to CO.
Three generations of metalated trigonal supramolecular architectures, so‐called metallo‐triangles, were assembled from terpyridine (tpy) complexes. The first generation (G1) metallo‐triangles were ...directly obtained by reacting a bis(terpyridinyl) ligand with a 60° bite angle and ZnII ions. The direct self‐assembly of G2 and G3 triangles by mixing organic ligands and ZnII, however, only generated a mixture of G1 and G2, as well as a trace amount of insoluble polymer‐like precipitate. Therefore, a modular strategy based on the connectivity of ⟨tpy−Ru2+−tpy⟩ was employed to construct two metallo‐organic ligands for the assembly of G2 and G3 Sierpiński triangles. The metallo‐organic ligands LA and LB with multiple free terpyridines were obtained through Suzuki cross‐coupling of the RuII complexes, and then assembled with ZnII or CdII to obtain high‐generation metallo‐triangular architectures in nearly quantitative yield. The G1–G3 architectures were characterized by NOESY and DOSY NMR spectroscopy, ESI‐MS, TWIM‐MS, and transmission electron microscopy.
Molecular Sierpiński triangles were assembled from rigid, puzzle‐like metallo‐organic ligands. As the self‐assembly of the second‐ and third‐generation (shown) Sierpiński triangles provided only product mixtures, a modular strategy based on the connectivity of tpy−RuII−tpy was developed to construct two metallo‐organic ligands for the assembly of these triangles.
The electroreduction of CO2 provides an attractive routine to produce hydrocarbons as an alternative of traditional petroleum chemical methods, as well as cobenefits the approach of CO2 emission ...control. Among various C2 hydrocarbons, C2H6 has the highest energy density but poor selectivity in CO2 electroreduction. Thus, the development of highly active catalysts and formation mechanism is desired. Herein, a facile method to synthesize iodide-doped Cu nanoarray (ID-Cu NA) catalysts and a strategy to boost C2H6 electrosynthesis was developed. ID-Cu NAs have dispersive iodide dopants on nanowires, which create a microenvironment to feed, stabilize, and hydrogenate C2H4. This catalyst displays a remarkable selectivity for C2H6 production. Impressively, ID-Cu NAs show a Faradaic efficiency of 24% for C2H6, five times higher than the corresponding Cu NAs before iodide doping. However, the Faradaic efficiency of C2H4 on Cu NAs decreases from 28 to 5% after iodide doping. The results of C2H4 electrodesorption and electrohydrogenation tests indicated that the iodide dopant contributed a more stable C2H4 adsorption and higher hydrogenation ability. Density functional theory calculations demonstrated that the doping of iodide helps to strengthen the adsorption of C2H4 on the Cu surface and lowers the energy barrier of the hydrogenation to C2H6, which simultaneously encourages C2H6 formation in CO2 electroreduction. This work also cleared up the origin of C2H6 formation in CO2 reduction reaction (CO2RR) in which a tandem pathway from CO2 → C2H4 to C2H4 → C2H6 is involved.
The dianthracene-based rhomboidal organoplatinum(II) metallacycle 1 was successfully obtained via coordination-driven self-assembly involving the combination of diplatinum(II) acceptor 2 and ...dipyridyl donor 3. A dilute acetone solution of the prepared metallacycle exhibited temperature-responsive fluorescence involving a gradual red-shifted fluorescent change from cyan to yellow over a wide temperature range from 77 to 297 K. Notably, a linear correlation was observed between the emission maximum and temperature in the low-temperature region from 77 to 137 K. Additionally, the supramolecular coordination complex in the solid state showed reversible mechanochromic fluorescence behavior with an obvious color change between green and yellow. Further investigation revealed that a morphology change before and after grinding was responsible for the observed mechanofluorochromic phenomenon. These studies provide new insight into the preparation of well-defined supramolecular organoplatinum(II) metallacycles capble of responding to multiple stimuli.
Five- and six-pointed star structures occur frequently in nature as flowers, snow-flakes, leaves and so on. These star-shaped patterns are also frequently used in both functional and artistic ...man-made architectures. Here following a stepwise synthesis and self-assembly approach, pentagonal and hexagonal metallosupramolecules possessing star-shaped motifs were prepared based on the careful design of metallo-organic ligands (MOLs). In the MOL design and preparation, robust ruthenium-terpyridyl complexes were employed to construct brominated metallo-organic intermediates, followed by a Suzuki coupling reaction to achieve the required ensemble. Ligand LA (VRu
X, V=bisterpyridine, X=tetraterpyridine, Ru=Ruthenium) was initially used for the self-assembly of an anticipated hexagram upon reaction with Cd
or Fe
; however, unexpected pentagonal structures were formed, that is, Cd
LA
and Fe
LA
. In our redesign, LB V(Ru
X)
was synthesized and treated with 60° V-shaped bisterpyridine (V) and Cd
to create hexagonal hexagram Cd
V
LB
along with traces of the triangle Cd
V
. Finally, a pure supramolecular hexagram Fe
V
LB
was successfully isolated in a high yield using Fe
with a higher assembly temperature.
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