scholarly journals Low-temperature gas-phase formation of indene in the interstellar medium

2021 ◽  
Vol 7 (1) ◽  
pp. eabd4044
Author(s):  
Srinivas Doddipatla ◽  
Galiya R. Galimova ◽  
Hongji Wei ◽  
Aaron M. Thomas ◽  
Chao He ◽  
...  
Keyword(s):  
Low Temperature ◽  
Interstellar Medium ◽  
Three Dimensional ◽  
Building Blocks ◽  
Bimolecular Reaction ◽  
Membered Ring ◽  
Organic Radical ◽  
Structural Reorganization ◽  
Molecular Building Blocks ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAHs) are fundamental molecular building blocks of fullerenes and carbonaceous nanostructures in the interstellar medium and in combustion systems. However, an understanding of the formation of aromatic molecules carrying five-membered rings—the essential building block of nonplanar PAHs—is still in its infancy. Exploiting crossed molecular beam experiments augmented by electronic structure calculations and astrochemical modeling, we reveal an unusual pathway leading to the formation of indene (C9H8)—the prototype aromatic molecule with a five-membered ring—via a barrierless bimolecular reaction involving the simplest organic radical—methylidyne (CH)—and styrene (C6H5C2H3) through the hitherto elusive methylidyne addition–cyclization–aromatization (MACA) mechanism. Through extensive structural reorganization of the carbon backbone, the incorporation of a five-membered ring may eventually lead to three-dimensional PAHs such as corannulene (C20H10) along with fullerenes (C60, C70), thus offering a new concept on the low-temperature chemistry of carbon in our galaxy.

Self-Assembly of Proteins into Three-Dimensional Structures Using Bio-Conjugation

2014 ◽  
Vol 1663 ◽  
Author(s):  
Garima Thakur ◽  
Kovur Prashanthi ◽  
Thomas Thundat
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Gold Surface ◽  
Building Blocks ◽  
Growth Conditions ◽  
Base Layer ◽  
Chemical Structures ◽  
Molecular Building Blocks ◽  
Ring Structures ◽  
Self Assembled

ABSTRACTSelf–assembly of molecular building blocks provides an interesting route to produce well-defined chemical structures. Tailoring the functionalities on the building blocks and controlling the time of self-assembly could control the properties as well as the structure of the resultant patterns. Spontaneous self-assembly of biomolecules can generate bio-interfaces for myriad of potential applications. Here we report self-assembled patterning of human serum albumin (HSA) protein in to ring structures on a polyethylene glycol (PEG) modified gold surface. The structure of the self-assembled protein molecules and kinetics of structure formation entirely revolved around controlling the nucleation of the base layer. The formation of different sizes of ring patterns is attributed to growth conditions of the PEG islands for bio-conjugation. These assemblies might be beneficial in forming structurally ordered architectures of active proteins such as HSA or other globular proteins.

scholarly journals Low temperature gas phase reaction rate coefficient measurements: Toward modeling of stellar winds and the interstellar medium

2019 ◽  
Vol 15 (S350) ◽  
pp. 382-383
Author(s):  
Niclas A. West ◽  
Edward Rutter ◽  
Mark A. Blitz ◽  
Leen Decin ◽  
Dwayne E. Heard
Keyword(s):  
Low Temperature ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Building Blocks ◽  
Rate Coefficients ◽  
Stellar Winds ◽  
Phase Reaction

AbstractStellar winds of Asymptotic Giant Branch (AGB) stars are responsible for the production of ∼85% of the gas molecules in the interstellar medium (ISM), and yet very few of the gas phase rate coefficients under the relevant conditions (10 – 3000 K) needed to model the rate of production and loss of these molecules in stellar winds have been experimentally measured. If measured at all, the value of the rate coefficient has often only been obtained at room temperature, with extrapolation to lower and higher temperatures using the Arrhenius equation. However, non-Arrhenius behavior has been observed often in the few measured rate coefficients at low temperatures. In previous reactions studied, theoretical simulations of the formation of long-lived pre-reaction complexes and quantum mechanical tunneling through the barrier to reaction have been utilized to fit these non-Arrhenius behaviours of rate coefficients.Reaction rate coefficients that were predicted to produce the largest change in the production/loss of Complex Organic Molecules (COMs) in stellar winds at low temperatures were selected from a sensitivity analysis. Here we present measurements of rate coefficients using a pulsed Laval nozzle apparatus with the Pump Laser Photolysis - Laser Induced Fluorescence (PLP-LIF) technique. Gas flow temperatures between 30 – 134 K have been produced by the University of Leeds apparatus through the controlled expansion of N2 or Ar gas through Laval nozzles of a range of Mach numbers between 2.49 and 4.25.Reactions of interest include those of OH, CN, and CH with volatile organic species, in particular formaldehyde, a molecule which has been detected in the ISM. Kinetics measurements of these reactions at low temperatures will be presented using the decay of the radical reagent. Since formaldehyde and the formal radical (HCO) are potential building blocks of COMs in the interstellar medium, low temperature reaction rate coefficients for their production and loss can help to predict the formation pathways of COMs observed in the interstellar medium.

Crystal Engineering: Strategies and Architectures

1997 ◽  
Vol 53 (4) ◽  
pp. 569-586 ◽  
Author(s):  
C. B. Aakeröy
Keyword(s):  
Molecular Structure ◽  
Crystal Engineering ◽  
Crystal Packing ◽  
Three Dimensional ◽  
Structural Data ◽  
Building Blocks ◽  
Intermolecular Forces ◽  
Design Strategies ◽  
Playing Field ◽  
Molecular Building Blocks

The area broadly described as crystal engineering is currently expanding at a brisk pace. Imaginative schemes for supramolecular synthesis, and correlations between molecular structure, crystal packing and physical properties are presented in the literature with increasing regularity. In practice, crystal engineering can be many different things; synthesis, statistical analysis of structural data, ab initio calculations etc. Consequently, we have been provided with a new playing field where chemists from traditionally unconnected parts of the spectrum have exchanged ideas, defined goals and made creative contributions to further progress not only in crystal engineering, but also in other disciplines of chemistry. Crystal engineering is delineated by the nature and structural consequences of intermolecular forces, and the way in which such interactions are utilized for controlling the assembly of molecular building blocks into infinite architectures. Although it is important to acknowledge that a crystal structure is the result of a subtle balance between a multitude of non-covalent forces, this article will focus on design strategies based upon the hydrogen bond and will present a range of approaches that have relied on the directionality and selectivity of such interactions in the synthesis of predictable one-, two- and three-dimensional motifs.

Unraveling Life's Building Blocks: Sculpture Inspired by Proteins

Leonardo ◽  
2013 ◽  
Vol 46 (1) ◽  
pp. 12-17 ◽  
Author(s):  
Julian Voss-Andreae
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Building Blocks ◽  
Holistic View ◽  
Algorithmic Approach ◽  
One Dimensional ◽  
Molecular Building Blocks ◽  
Geometric Elements ◽  
Point Of Departure

Inspired by proteins, the molecular building blocks of life, the author's presented work re-creates the first step of the emergence of three-dimensional bodies from one-dimensional DNA. Utilizing an algorithmic approach as his point of departure, the artist follows his vision freely, creating sculptures that bring life's isolated components emotionally back to life. In this sequel to an earlier Leonardo article on the inception of his protein-inspired sculptures, the author presents the unfolding of his vision: Large-scale works of increasing formal and conceptual complexity display the emergence of an organic aesthetic from geometric elements and inspire a more holistic view of nature than that provided by reductionist science alone.

scholarly journals From time dependent incorporation of molecular building blocks to application properties for inorganic and organic three-dimensional network polymers

2020 ◽  
Author(s):  
Lies De Keer ◽  
Karsu Kilic ◽  
Paul Van Steenberge ◽  
Lode Daelemans ◽  
Daniel Kodura ◽  
...  
Keyword(s):  
Structural Information ◽  
Kinetic Monte Carlo ◽  
Chemical Reactivity ◽  
Three Dimensional ◽  
Building Blocks ◽  
Structure Property ◽  
Dynamic Simulations ◽  
Application Range ◽  
Molecular Building Blocks ◽  
Kinetic Monte Carlo Simulations

Abstract The three-dimensional configurational arrangement of natural and synthetic network materials determines their application range. Control of the real time incorporation of each building block, hence, all functional groups is desired so that we can regulate macroscopic properties from the molecular level onwards. Here we interconnect kinetic Monte Carlo simulations from the field of chemical kinetics and molecular dynamic simulations from the field of physics. We visualize for (in)organic network material synthesis how the initial building blocks interact timewise and spatially, accounting for variations in inter- and intramolecular chemical reactivity, diffusivity, segmental compositions, branch/network point locations, and defects. We use the kinetic and three-dimensional structural information to construct structure-property relationships based on molecular descriptors such as the molecular pore size or dangling chain distribution, differentiating between ideal and non-ideal structural elements. The generic nature is illustrated by constructing such relationships for the synthesis of organosilica, epoxy-amine and Diels-Alder based networks.

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