Shubin Liu

• Ph.D
• Researcher at University of North Carolina at Chapel Hill

The density-based descriptors from the information-theoretic approach (ITA) are used as features for multiproperty deep learning (DL), predicting the correlation energy and physicochemical properties of molecules. In addition to response properties (molecular polarizability α iso and NMR shielding constant σ iso) where ITA has been shown to work we...

In this survey, we begin with a concise introduction to information theory within Shannon's framework, focusing on the key concept of Shannon entropy and its related quantities: relative entropy, joint entropy, conditional entropy and mutual information. We then demonstrate how to apply these information-theoretic tools in quantum chemistry, adopti...

We have witnessed a recent surge in the development and application of the information-theoretic approach in density functional theory. In this minireview, focusing on our own work in recent years about this topic, we highlight its theoretical framework, including four representations, three principles and two identities, illustrate four examples o...

Chikungunya virus (CHIKV) replication relies on the multifunctional nsP2 protein, making it an attractive target for antiviral drug discovery. Here, we report the resolution of oxaspiropiperidine 1 , a first-in-class inhibitor of the CHIKV nsP2 RNA helicase (nsP2hel), into its constitutive enantiomers and characterization of their antiviral activit...

Covalent bonding and noncovalent interactions are important chemical concepts and how to identify them has been of current interest in the literature. Within the framework of density functional theory (DFT), we recently proposed a few qualitative descriptors to categorize different types of interactions with Pauli energy and its derivatives. In thi...

Excited states are essential to many chemical processes in photosynthesis, solar cells, light-emitting diodes, and so on, yet how to formulate, quantify, and predict physiochemical properties for excited states from the theoretical perspective is far from being established. In this work, we leverage the four density-based frameworks from density fu...

We rationalize the excellent performance of information-theoretic descriptors for predicting atomic and molecular polarizabilities. It seems that descriptors which capture information about the change in valence-shell structure, especially the relative Fisher information measures, are particularly useful. Using this, we can rationalize why the G3 f...

Electrophilicity and nucleophilicity are two vastly important chemical concepts gauging the capability of atoms in molecules to accept and donate the maximal number of electrons. In our earlier studies, we proposed to simultaneously quantify them using the Kullback–Leibler divergence from the information-theoretic approach in density functional the...

Appreciating reactivity in terms of physicochemical effects for chemical processes is one of the most important undertakings in chemistry. While transition state (TS) theory provides the framework enabling the reliable calculation of the barrier height for a given elementary step, analytical tools are necessary to gain insight into key factors gove...

The steric effect is one of the most widely used concepts for chemical understanding in publications and textbooks, yet a well-accepted formulation of this effect is still elusive. Experimentally, this...

Fused-ring electronic acceptors (FREAs) have transformed the field of organic solar cells. However, the prevailing syntheses of FREAs suffer from low yield, difficulty in separation, and high cost. Here, we report new and streamlined syntheses with three distinctive key steps. First, a universal approach to fuse neighboring aromatic units via a sin...

The enantioenriched lactams disclosed in this work are synthesized concisely in four steps. In the penultimate reaction, a benzylamine species complexes with a chiral phosphoric acid to produce benzo-fused δ-lactams equipped with an all-carbon quaternary stereocenter. Partial and full reductions were carried out on the ester and amide moieties, and...

Methods enabling the broad diversification of C(sp³)−H bonds from a common intermediate are especially valuable in chemical synthesis. Herein, we report a site‐selective (N‐phenyltetrazole)thiolation of aliphatic and (hetero)benzylic C(sp³)−H bonds using a commercially available disulfide to access N‐phenyltetrazole thioethers. The thioether produc...

Methods enabling the broad diversification of C(sp3)–H bonds from a common intermediate are especially valuable in chemical synthesis. Herein, we report a site‐selective (N‐phenyltetrazole)thiolation of aliphatic and (hetero)benzylic C(sp3)–H bonds using a commercially available disulfide to access N‐phenyltetrazole thioethers. The thioether produc...

Flexible electronics have received considerable attention in the past decades due to their promising application in rollable display screens, wearable devices, implantable devices, and other electronic applications. In particular, conjugated polymers are favored for flexible electronics due to their mechanical flexibility and potential for solution...

QM/MM methods have been used to study electronic structure properties and chemical reactivity in complex molecular systems where direct electronic structure calculations are not feasible. In our previous work, we showed that non-polarizable force fields, by design, describe intermolecular interactions through pairwise interactions, overlooking many...

In this work, we have observed that some chiral boron clusters (B16−, B20−, B24−, and B28−) can simultaneously have helical molecular orbitals and helical spin densities; these seem to be the first compounds discovered to have this intriguing property. We show that chiral Jahn–Teller distortion of quasi-planar boron clusters drives the formation of...

Simultaneous prediction of the molecular response properties, such as polarizability and the NMR shielding constant, at a low computational cost is an unresolved issue. We propose to combine a linear-scaling generalized energy-based fragmentation (GEBF) method and deep learning (DL) with both molecular and atomic information-theoretic approach (ITA...

Helical (frontier) molecular orbitals [Chem. Sci. 2013, 4, 4278] have been reported almost a decade ago. Yet, helical molecular spin densities [Mol. Phys. 2022, e2157774] have been observed by us only very recently. In this work, we have observed that some chiral boron clusters (B–16, B–20, B–24, and B–28) can simultaneously have helical molecular...

It is tenable to argue that nobody can predict the future with certainty, yet one can learn from the past and make informed projections for the years ahead. In this Perspective, we overview the status of how theory and computation can be exploited to obtain chemical understanding from wave function theory and density functional theory, and then out...

Polymorphic transformation of molecular crystals is a fundamental phase transition process, and it is important practically in the chemical, material, biopharmaceutical, and energy storage industries. However, understanding of the transformation...

It is tenable to argue that nobody can predict the future with certainty, yet one can learn from the past and make informed projections for the years ahead. In this Perspective article, we overview the status of how theory and computation can be exploited to obtain chemical understanding from wave function theory and density functional theory, and...

Strong and weak interatomic interactions in chemical and biological systems are ubiquitous, yet how to identify them on a unified theoretical foundation is still not well established. Recently, we proposed employing Pauli energy-based indexes, such as strong covalent interaction and bonding and noncovalent interaction indexes, in the framework of d...

QM/MM methods have been used to study electronic structure properties and chemical reactivity in complex molecular systems where direct electronic structure calculations are not feasible. In our previous work, we showed that non-polarizable force fields, by design, describe intermolecular interactions through pairwise interactions, overlooking many...

Understanding cooperativity and frustration is crucial for studying biological processes such as molecular recognition and protein aggregation. Force fields have been extensively utilized to explore cooperativity in the formation of protein secondary structures and self-assembled systems. Multiple studies have demonstrated that polarizable force fi...

Our recent study [M. Li et al.Phys. Chem. Chem. Phys., 2023, 25, 2595-2605] unveiled that the impact of an external electric field on molecular acidity and aromaticity for benzoic acid is directional, which can be understood using changes in frontier orbitals and partial charges. However, it is unclear if the effect will disappear when substituting...

Diene)Rh(I) complexes catalyze the stereoselective three‐component coupling of silyl glyoxylates, arylboronic acids, and aldehydes to give glycolate aldol products. The participation of Rh‐alkoxides in the requisite Brook rearrangement was established through two component Rh‐catalyzed couplings of silyl glyoxylates with ArB(OH)2 to give silyl‐prot...

To accurately and efficiently predict the molecular response properties (such as polarizability) at post-Hartree−Fock levels for condensed-phase systems under periodic boundary conditions (PBC) is still an unaccomplished and ongoing task. We demonstrate that static isotropic polarizabilities can be cost-effectively predicted at post-Hartree−Fock le...

(Diene)Rh(I) complexes catalyze the stereoselective three‐component coupling of silyl glyoxylates, arylboronic acids, and aldehydes to give glycolate aldol products. The participation of Rh‐alkoxides in the requisite Brook rearrangement was established through two component Rh‐catalyzed couplings of silyl glyoxylates with ArB(OH)2 to give silyl‐pro...

Using density-based quantities to establish a qualitative or even quantitative framework to predict molecular reactivity in density functional theory is of considerable interest in the current literature. Recent developments in information-theoretic approach (ITA) represent such a trend. Traditionally, we represent ITA quantities in terms of the el...

As one of the founders of quantum chemistry, Robert G. Parr (RGP) was an influential theoretical chemist of the last few decades. He made enormous scientific contributions to both wave function theory and density functional theory. He was also the founding father of conceptual density functional theory. RGP was both a devoted scientist and a family...

Synthetic, structural, and computational approaches were used to solve the puzzle as to how a phenolic nonsteroidal estrogen 1 with only a single H‐bond to its receptor was more potent than an isomer 2 which formed an intricate network of H‐bonds. Synthesis of a series of substituted phenols revealed that pKa was not a determinant of estrogenic act...

We have witnessed considerable research interest in the recent literature about the development and applications of quantities from the information-theoretic approach (ITA) in density functional theory. These ITA quantities are explicit density functionals, whose local distributions in real space are continuous and well-behaved. In this work, we fu...

Alkanes are deceptively simple in their geometric structures, yet their electronic structures are a tough nut to crack. We employ two total energy partition schemes in density functional theory and the information-theoretic approach quantities to dissect the so-called isomerization problem. From our validation results, we have found theoretical met...

Understanding cooperativity and frustration is crucial for studying biological processes, such as molecular recognition and protein aggregation. Force fields have been extensively utilized to explore cooperativity in the formation of protein secondary structures and self-assembled systems. Multiple studies have demonstrated that polarizable force f...

Using density-based quantities to establish a qualitative or even quantitative framework to predict molecular reactivity in density functional theory is of considerable interest in the current literature. Recent developments in information-theoretic approach (ITA) represent such a trend. Traditionally, we represent ITA quantities in terms of the el...

We develop an efficient method to compute the electrostatic component of the solvation free energy via the two-point Padé approximation. The Padé approximant uses four parameters to describe the electrostatic free energy change of the solvation process, which could be readily determined from four thermodynamic properties obtained in two simulations...

Synthetic, structural, and computational approaches were used to solve the puzzle as to how a phenolic nonsteroidal estrogen 1 with only a single H-bond to its receptor was more potent than an isomer 2 which formed an intricate network of H-bonds. Synthesis of a series of substituted phenols revealed that pKa was not a determinant of estrogenic act...

A bifunctional iminophosphorane (BIMP)-catalyzed method for the synthesis of densely functionalized cyclohexanols establishes five contiguous stereocenters (diastereoselection up to >20:1, enantioselectivity up to >99:1) in a Michael/aldol domino reaction between trisubstituted electrophilic alkenes and γ-nitroketones. Mechanistic studies suggest a...

Designing efficient and selective catalysts for carbon dioxide reduction is an intensive research area in the recent literature on homogeneous catalysis. In this work, we study the catalytic activity of a newly reported Mn(I)-PNP-pincer catalyst with an embedded aromatic ring. First, we systematically examine its capability to yield different produ...

Accurate and efficient determination of excited-state polarizabilities (α) is an open problem both experimentally and computationally. Following our previous work, (Phys. Chem. Chem. Phys. 2023, 25, 2131−2141), in which we employed simple ground-state (S0) density-related functions from the information-theoretic approach (ITA) to accurately and eff...

Accurate and efficient determination of excited-state polarizabilities (α) is an open problem both experimentally and computationally. Following our previous work, [Phys. Chem. Chem. Phys. 2023, 25, 2131−2141], where one can employ simple ground-state density-based functions from the information-theoretic approach (ITA) to accurately and efficientl...

Triatomic H3⁺ and Li3⁺ clusters play a crucial role in astrophysics, taking part in the early transformations responsible for the formation of stars. In this contribution, a few analytical tools are employed to dissect and compare their properties in bonding, aromaticity, and reactivity. We find that H3⁺ and Li3⁺, though simple and similar in struc...

Alkanes are deceptively simple in their geometric structures, yet their electronic structures are a tough nut to crack. We employ two total energy partition schemes in density functional theory and the information-theoretic approach quantities to dissect the so-called isomerization problem. From our validation results, we have found theoretical met...

Accurately and efficiently predicting macromolecules' polarizabilities is an open problem. In this work, we employ a few simple density-based quantities from the information-theoretic approach (ITA) to predict polarizability of proteins. We first build quantitative structure/property relationships between molecular polarizabilities and ITA quantiti...

The Ramachandran plot in biochemistry visualizes the propensity of amino acid residues to assume different secondary structures. It can be obtained by different approaches such as bioinformatics and molecular dynamics. In this work, we systematically scan the two single bonds around the α‐carbon of a peptide to generate the three‐dimensional potent...

Chunying Rong (2022): Cooperativity and reactivity properties of medium-sized boron clusters: a combined density functional theory and information-theoretic approach study, Molecular Physics, ABSTRACT In continuation of our previous work of small boron clusters [Phys. Chem. Chem. Phys. 23, 24118 (2021)], we systematically examined the neutral and n...

Malaria is a devastating disease that causes significant global morbidity and mortality. The rise of drug resistance against artemisinin-based combination therapy demonstrates the necessity to develop alternative antimalarials with novel mechanisms of action. We report the discovery of Ki8751 as an inhibitor of essential kinase PfPK6. 79 derivative...

Density functional theory, which is well-recognized for its accuracy and efficiency, has become the workhorse for modeling the electronic structure of molecules and extended materials in recent decades. Nevertheless, establishing a density-based conceptual framework to appreciate bonding, stability, function, reactivity, and other physicochemical p...

Catalytic carbonylations of aryl electrophiles via C(sp²)−N cleavage remains a significant challenge. Herein, we demonstrate an aminocarbonylation of aniline‐derived trialkylammonium salts promoted by visible light with a simple cobalt catalyst. The reaction proceeds under mild conditions suitable for late‐stage functionalization and is amenable to...

Using the energy components associated with density-functional theory (DFT) calculations and various descriptors from the density-functional reactivity theory (conceptual DFT), we explore which chemical effects are most important for determining the ordering the conformers of the twenty natural amino acids in terms of their relative energetic stabi...

In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchan...

Internal methyl rotation is a ubiquitous phenomenon in chemistry and could find ample implications in other disciplines, where structure, reactivity, and function properties are impacted. It is commonly believed that steric effect is dominant in governing the rotation barrier height. In this work, we make use of the two total energy partition schem...

Density functional theory well-recognized by its accuracy and efficiency has become the workhorse for modeling the electronic structure of molecules and extended materials in the past decades. Nevertheless, how to establish a density-based conceptual framework to appreciate bonding, stability, function, reactivity, and other physiochemical properti...

Catalytic carbonylations of aryl electrophiles via C(sp 2 )–N cleavage remains a significant challenge. Herein, we demonstrate an aminocarbonylation of aniline‐derived trialkylammonium salts promoted by visible light with a simple cobalt catalyst. The reaction proceeds under mild conditions suitable for late‐stage functionalization and is amenable...

Energy and information are two fundamental concepts in physics and chemistry. In density functional theory (DFT), all information pertaining to stability, reactivity, and other properties is encompassed in the ground state electron density. The basic theorems of DFT govern that energy is a universal functional of the density and thus it can be rega...

In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchan...

A mechanistic investigation into the amination of electron-neutral and electron-rich arenes using organic photoredox catalysis is presented. Kinetic and computational data support rate-limiting nucleophilic addition into an arene cation radical using both azole and primary amine nucleophiles. This finding is consistent with both fluoride and alkoxi...

Using density functional theory (DFT) and the information-theoretic approach (ITA) quantities to appreciate the energetics and properties of biopolymers is still an unaccomplished and ongoing task. To this end, we studied the building blocks of nucleic acid base pairs and small peptides. For base pairs, we have dissected the relative importance of...

In the first paper of this series, the authors derived an expression for the interaction energy between two reagents in terms of the chemical reactivity indicators that can be derived from density functional perturbation theory. While negative interaction energies can explain reactivity, reactivity is often more simply explained using the “|dμ| big...

Using density functional theory (DFT) and the information-theoretic approach (ITA) quantities to appreciate the energetics and properties of biopolymers is still an unaccomplished and ongoing task. To this end, we studied the building blocks of nucleic acid base pairs and small peptides. For base pairs, we have dissected the relative importance of...

Energy and information are two fundamental concepts in physics and chemistry. In density functional theory (DFT), all information pertaining to stability, reactivity, and other properties is encompassed in the ground state electron density. The basic theorems of DFT govern that energy is a universal functional of the density and thus it can be rega...

In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchan...

Malaria is a devastating disease that causes significant global morbidity and mortality. The rise of drug resistance against artemisinin-based combination therapy, the frontline treatment for malaria, demonstrates the necessity to develop alternative antimalarials with novel mechanisms of action. Inhibition of Plasmodium protein kinases presents an...

In this chapter, we introduce the basic framework of conceptual density functional theory (CDFT). After a brief introduction of the Legendre transform, the four ensembles of CDFT are presented, including the canonical ensemble, grand canonical ensemble, isomorphic ensemble, and grand isomorphic ensemble. Partial and functional derivatives in these...

This chapter introduces the information‐theoretic approach (ITA) in conceptual density functional theory (CDFT). Different from traditional approaches in CDFT, where first‐ and second‐order derivatives are utilized to quantify chemical reactivity, ITA directly employs density functionals for the purpose. Their analytical forms in terms of density a...

This chapter focuses on three applications of conceptual density functional theory (CDFT) to appreciate molecular acidity for organic and inorganic compounds, proton‐coupled electron transfer (PCET) reactions for biologically relevant complexes, and metal specificity for porphyrins. With two interdependent descriptors, molecular electrostatic poten...

Designing compounds with as long carbon‐carbon bond distances as possible to challenge conventional chemical wisdom is of current interest in the literature. These compounds with exceedingly long bond lengths are commonly believed to be stabilized by dispersion interactions. In this work, we build nine dimeric models with varying sizes of alkyl gro...

The impact of external fields on the molecular structure and reactivity properties has been of considerable interest in the recent literature. Benzoic acid as one of the most widely used compounds in medicinal and materials sciences is known for its dual propensity in aromaticity and acidity. In this work, we systematically investigate the impact o...

Designing compounds with as long carbon-carbon bond distances as possible to challenge conventional chemical wisdom is of current interest in the literature. These compounds with exceedingly long bond lengths are commonly believed to be stabilized by dispersion interactions. In this work, we build nine dimeric models with varying sizes of alkyl gro...

Chemical bonds and noncovalent interactions are extraordinarily important concepts in chemistry and beyond. Using density-based quantities to describe them has a long history in the literature, yet none can satisfactorily describe the entire spectrum of interactions from strong chemical bonds to weak van der Waals forces. In this work, employing Pa...

Atomic clusters are unique in many perspectives because of their size and structure features and are continuously being applied for different purposes. To unveil their unconventional properties, in this work, using neutral tetraboron clusters as illustrative examples, we study their exotic behaviors in bonding, aromaticity, and reactivity. We show...

How to quantitatively appreciate the nature and origin of rotation barriers arising from conformational changes of biologically and pharmaceutically essential molecules is of considerable current interest in the literature. In this work, using porphyrinoid derivatives as examples, we examine their conformational changes in different charge and spin...

Confined quantum systems have attracted considerable research interest in the literature largely because of the change of their peculiar physicochemical properties induced by the confinement effect. Of many such examples, endohedral fullerenes have been extensively investigated from both epistemological and application viewpoints. This chapter cons...

There are different kinds of molecular chirality, such as zero-dimensional point chirality, one-dimensional axial chirality, 2D planar chirality, and 3D chirality. When they coexist in one system, such as in helical structures of proteins and DNA, they form a chirality hierarchy. Earlier, we showed that the chirality propensity of a lower level in...

There are different kinds of molecular chirality, such as zero-dimensional point chirality, one-dimensional axial chirality, 2D planar chirality, and 3D chirality. When they coexist in one system, such as in helical structures of proteins and DNA, they form a chirality hierarchy. Earlier, we showed that the chirality propensity of a lower level in...

Ambient ionization of glycans is simply and efficiently achieved by spraying from an alkali metal salt-impregnated paper surface. Monosaccharides, oligosaccharides and ring glycans easily form abundant alkali metal adduct ions, and give simple and clean high-quality mass spectra. The enhancement is specific for glycans, compared to a wide variety o...

Though density functional theory is widely accepted as one of the most successful developments in theoretical chemistry in the past few decades, the knowledge of how to apply this new electronic structure theory, to help us better understand chemical processes and transformations, is still an unaccomplished task. The information-theoretic approach...

Allylic alcohols, as common and readily available building blocks, could be converted into many widely used carbonyl compounds through isomerization reactions. However, these processes often involve expensive transition metal (TM) complexes as the catalyst. What is the bottleneck in the mechanism when no TM is used? In this study, density functiona...