On-surface polymerization represents a novel bottom-up approach for producing macromolecular structures. To date, however, most of the structures formed using this method exhibit a broad size distribution and are disorderly adsorbed on the surface. Here we demonstrate a strategy of using metal-directed template to control the on-surface polymerization process. We chose a bifunctional compound which contains pyridyl and bromine end groups as the precursor. Linear template afforded by pyridyl-Cu-pyridyl coordination effectively promoted Ullmann coupling of the monomers on a Au(111) surface. Taking advantage of efficient topochemical enhancement owing to the conformation flexibility of the Cu-pyridyl bonds, macromolecular porphyrin structures that exhibit a narrow size distribution were synthesized. We used scanning tunneling microscopy and kinetic Monte Carlo simulation to gain insights into the metal-directed polymerization at the single molecule level. The results reveal that the polymerization process profited from the rich chemistry of Cu which catalyzed the C-C bond formation, controlled the size of the macromolecular products, and organized the macromolecules in a highly ordered manner on the surface.

On-surface Pd- and Cu-catalyzed C-C coupling reactions between phenyl bromide functionalized porphyrin derivatives on an Au(111) surface have been investigated under ultra-high vacuum conditions by using scanning tunneling microscopy and kinetic Monte Carlo simulations. We monitored the isothermal reaction kinetics by allowing the reaction to proceed at different temperatures. We discovered that the reactions catalyzed by Pd or Cu can be described as a two-phase process that involves an initial activation followed by C-C bond formation. However, the distinctive reaction kinetics and the C-C bond-formation yield associated with the two catalysts account for the different reaction mechanisms: the initial activation phase is the rate-limiting step for the Cu-catalyzed reaction at all temperatures tested, whereas the later phase of C-C formation is the rate-limiting step for the Pd-catalyzed reaction at high temperature. Analysis of rate constants of the Pd-catalyzed reactions allowed us to determine its activation energy as (0.41±0.03) eV.

Intermolecular benzylic methylene functionalization of exo-cyclic enol ethers has been achieved using imines as reagents and potassium tert-butoxide as the catalyst. Depending on the solvent used, the reaction proceeds by two pathways. In THF, an addition/elimination reaction of exo-cyclic enol ethers with imines provides dihydroisobenzofuran derivatives in good yield. In DMSO, an addition/ring-opening/cyclization cascade reaction occurs with unexpected cleavage of C-O and C-C bonds, affording isoquinolin-1(2H)-one products in high yield under ambient reaction conditions.

Using scanning tunneling microscopy, the coordination self-assembly of a series of peripheral bromo-phenyl and pyridyl substituted porphyrins with Fe was studied on an Au(111) surface. The porphyrins functionalized with two trans-pyridyl groups afford extended hexagonal frameworks and the porphyrins functionalized with three pyridyl groups generate discrete rosette and extended chiral kagome framework structures. The self-assembly of the porphyrin derivatives in which phenyl groups are substituted by bromo-phenyl results in coordination networks exhibiting identical structures to that of the parent compounds. These structures contain nanocavities decorated with Br, which provide potential for covalent functionalization.

Holters may accommodate the demand of daily health monitoring of hearts. [14][15][16] But current ECG monitoring systems either contain small numbers of leads that are used as consumer electronics for diagnosing limited numbers of symptoms [17][18][19][20] or contains multiple rigid leads that are prone to the influence of motions and are unable to conduct dynamic measurement. [21,22] Flexible electronic systems have demonstrated their capabilities in adapting skin contour and skin motion, minimizing the issues of motion artifacts and mechanical mismatches between conventional rigid electronic materials and soft skin. They have been demonstrated as varieties of wearable sensing patches to record physical parameters such as temperature, [23,24] humidity, [25][26][27] blood pressure, [28][29][30] and strain [31,32] as well as chemicals such as ions, [33,34] glucose, [35,36] and blood oxygen. [37,38] Flexible ECG systems have also been explored in the context of stretchable electrodes, [39,40] novel conductive electrode materials, [40][41][42][43] capacitive sensing, [44,45] and flexible hybrid electronics. [46][47][48] However, the majority of these ECG systems are based on single lead detection with a small sensing area, lacking the capability to comprehensively probe the hearts from different angles and the compatibility with clinical standards that are built on 12-lead ECG. [49,50] Flexible 12-lead ECG systems may offer precise and comprehensive detection results that abide by the clinical requirements with excellent tolerance to body motion and skin contour. However, such systems have seldomly been reported due to the complexity in constructing flexible systems that cover large surface areas while maintaining high stability in motion and skin deformation. As a result, a flexible 12-lead system in integrating with skin and potential influence factors to the performance of this system has rarely been studied.Here, we developed a flexible 12-lead ECG system that can simultaneously conduct electrocardiogram sensing and threeaxis acceleration monitoring. The system that contains a flexible sensor formed by modularized components and a flexible wireless measurement circuit. The sensing components are screen-printed and assembled to cover almost the entire chest area with adjustable dimensions to adapt to different body shapes. The design of individual components in the sensor Dynamic multilead monitoring of cardiovascular health conditions is challenging due to the complexity of constructing a flexible system that covers large surface areas and synchronizes measurement results from different leads. A flexible 12-lead electrocardiography system that can simultaneously conduct electrocardiogram sensing and 3-axis acceleration monitoring is developed. The system is fabricated through a modularized printing process, resulting in individual modules that can be assembled reversibly through magnetic connectors. Different levels of stretchability and adjustable length of interconnect can accommodate different body statures a...