About

Professor Raúl Hernández Sánchez leads the Hernández Sánchez Research Group at Rice University's Department of Chemistry. His research group focuses on innovative chemistry involving molecular structures such as contorted aromatic species, metal cluster dimerization, and the synthesis of highly strained deep cavitands. The group has made significant contributions to the understanding of exciton trapping at molecular nanotubes, the synthesis of nanogloves, and the binding of fullerenes, as well as the development of new ligand systems for dinuclear compounds. Professor Hernández Sánchez's work also extends to electrocatalytic cracking of alkanes and carbon dioxide reduction chemistry, supported by various grants including from the Welch Foundation and the NSF. He has been recognized for his scientific achievements, including being named to "The Atlas of Inspiring Hispanic/Latinx Scientists" and being selected as part of C&EN News' Talented 12 class of 2023. His group actively collaborates with other researchers and institutions, contributing to advancements in synthetic chemistry and materials science.

Research topics

• Chemistry
• Organic chemistry
• Materials science
• Computer Science
• Nanotechnology
• Photochemistry
• Crystallography
• Composite material
• Biology

Selected publications

• Challenges and Opportunities in PFAS Waste Management for Semiconductor Manufacturing

  Environmental Science & Technology · 2026-01-14 · 2 citations

  article

  Semiconductor manufacturing is rapidly expanding alongside tightening environmental regulations and increasing public concern around per- and polyfluoroalkyl substances (PFAS). Because of their unique chemical properties, PFAS are used across numerous processes in semiconductor manufacturing. Given process complexity and lengthy development timelines for alternatives, eliminating PFAS use in this industry is not currently feasible. Developing practical technologies for PFAS waste management is therefore critical but uniquely challenging in semiconductor manufacturing due to the nature of waste streams (parts-per-billion PFAS concentrations, complex backgrounds including hundreds of chemicals, prevalence of ultrashort PFAS, total stream volumes up to 35,000 m3 per day per facility, and distribution across gas, liquid, and solid phases) and significant constraints on space and systems redesign. This review describes recent developments and key questions that must be addressed to develop impactful and commercially viable detection and abatement methods for PFAS waste management in semiconductor manufacturing. Integrating these technologies into compact, high-performance systems and testing them under realistic conditions (complex PFAS mixtures, high fluoride/ionic strength, pH 6–11, low contact time, process variability) through industrial collaborations is essential for scalable, cost-effective solutions. Research addressing semiconductor industry-specific PFAS waste is essential to enable environmental compliance while supporting the continued growth of semiconductor manufacturing.

  PublisherDOI

• Activation of Dioxygen via Neodymium-Alkali Metal Clusters

  Journal of the American Chemical Society · 2026-03-20

  articleOpen accessSenior authorCorresponding

  The discovery of new dioxygen binding and activation modes is of paramount importance in biological and synthetic systems. Herein, we describe two rare earth-alkali metal clusters displaying unusual reactivity with dioxygen. We isolate a trans-end-on peroxo dineodymium tetrapotassium species, (LH4Nd)2(trans-μ-η1:η1-O2)K4(thf)4 (5), from reduction reactions of LH5Nd (1) and K[LH4Nd] (2) employing KC8 in dry O2. Cluster 5 contains the first end-on peroxo coordination to an f-block metal. Surprisingly, when the weaker reductant sodium naphthalenide (Na[C10H8]) is used, we isolate the cluster (LH4Nd)2(μ6-O)Na4(thf)4 (6), indicating dioxygen’s O–O bond has been cleaved. The typically weak π-backbonding interaction of 4f-block elements to stabilize the end-on binding mode of O2 is realized in 5 through a Lewis acid-assisted support of the peroxo species. Cleaving of the O–O bond in 6 is attributed to an increased Lewis acid effect rather than a larger chemical potential driving force since |Ered(KC8)| > |Ered ([C10H8]−|. Lanthanide oxos are highly reactive; however, the oxo reactivity in 6 is tamed by dimerization and protection with four equatorial closely associated Na ions. This work demonstrates a synergistic effect between the rare earth and alkali metals in the binding and activation of dioxygen and provides a novel route to examine lanthanide peroxo/oxo chemistry.

  PublisherDOI

• Disentangling the Noncovalent Interactions That Drive Coinage Metal Cluster Dimerization

  The Journal of Physical Chemistry A · 2025-08-11 · 5 citations

  articleCorresponding

  Understanding the atomistic interactions that drive self-assembly is a fundamental topic of broad interest in the design of supramolecular materials. The involvement of transition metal centers substantially enhances the number and types of interactions available in synthesizing designer chemical aggregates. In this work, we experimentally isolate supramolecular dimeric clusters of tetranuclear coinage metal (Cu, Ag, Au) monomers in the solid-state that adopt a cofacial [M4]–[M4] arrangement and exhibit short metal–metal distances and close M···H–C contacts. Through quantum chemical investigations, including atoms-in-molecules (AIM), noncovalent interaction (NCI), and local energy decomposition (LED) analysis, along with proton NMR chemical shift calculations, we establish the existence of anagostic (and metallophilic) interactions that increase in strength going from Cu to Ag to Au. We proceeded to quantify the relative contributions of various interactions to the observed dimerization. We find that multiple individually weak but cumulatively significant noncovalent interactions drive dimerization, with interligand dispersion the most prominent (24–34 kcal/mol), followed by hydrogen bonding; metallophilic and anagostic interactions contribute 2–9 and 2–6 kcal/mol, respectively. Taken together, we establish that myriad noncovalent interactions can synergistically guide the precise formation of strongly bound coinage metal dimers.

  PublisherDOI

• Cyclen-Based Octaamine Ligand Supporting the Formation of Dinuclear Metal Compounds

  Inorganic Chemistry · 2025-03-24 · 8 citations

  articleSenior authorCorresponding

  A series of divalent first-row dinuclear transition metal complexes─LCr2, LMn2, LFe2, LCo2, and LZn2─are synthesized and characterized using a 1,4,7,10-tetraazacyclododecane (cyclen)-derived octaamine ligand (LH4) as a dinucleating platform. The ligand scaffold stabilizes these complexes without the need of exogenous ligands to complete the coordination sphere, giving rise to coordinatively unsaturated complexes. Crystallographic analysis reveals that the Mn, Fe, Co, and Zn complexes are isostructural, adopting coordination environments with the metal atoms situated in pseudotetrahedral and square pyramidal environments. In contrast, the Cr complex exhibits a structure where the two metal atoms reside in identical and cofacial pseudo-square planar geometries. DFT calculations, electron localization function analysis, and Wiberg bond indices suggest varying degrees of metal–metal bonding interactions across all complexes described here. In LCr2, the short Cr–Cr distance of 1.9609(7) Å is consistent with a quadrupole bond, which is supported by DFT calculations. These results demonstrate the utility of this cyclen-based ligand scaffold in templating the synthesis of dinuclear complexes establishing a range of weak, in the case of the isostructural LMn2, LFe2, LCo2, and LZn2, to strong metal–metal interactions in LCr2. The dinuclear complexes supported by weak field amido and amine donors in LH4 represent a promising platform to investigate biomimetic cooperative small molecule activation.

  PublisherDOI

• Catching Fullerenes: Synthesis of Molecular Nanogloves

  Angewandte Chemie · 2025-05-01

  articleOpen accessSenior author

  Abstract Herein, we report the synthesis of a new series of rigid, all meta ‐phenylene, conjugated deep‐cavity molecules, displaying high binding affinity towards buckyballs. A facile synthetic approach with an overall combined yield of approximately 53% in the last two steps has been developed using a templating strategy that combines the general structure of resorcin[4]arene and [12]cyclo‐ meta ‐phenylene. These two moieties are covalently linked via four acetal bonds, resulting in a glove‐like architecture. 1 H NMR titration experiments reveal fullerene binding affinities ( K a ) exceeding ≥10 6 M −1 . The size complementarity between fullerenes and these scaffolds maximizes CH⋯π and π⋯π interactions, and their host:guest adduct resembles a ball in a glove, hence their name as nanogloves. Fullerene recognition is tested by suspending carbon soot in a solution of nanoglove in 1,1,2,2‐tetrachloroethane, where more than a dozen fullerenes are observed, ranging from C 60 to C 96 .

  PublisherOA PDFDOI

• Catching Fullerenes: Synthesis of Molecular Nanogloves

  Angewandte Chemie International Edition · 2025-05-01 · 4 citations

  articleOpen accessSenior authorCorresponding

  Abstract Herein, we report the synthesis of a new series of rigid, all meta ‐phenylene, conjugated deep‐cavity molecules, displaying high binding affinity towards buckyballs. A facile synthetic approach with an overall combined yield of approximately 53% in the last two steps has been developed using a templating strategy that combines the general structure of resorcin[4]arene and [12]cyclo‐ meta ‐phenylene. These two moieties are covalently linked via four acetal bonds, resulting in a glove‐like architecture. 1 H NMR titration experiments reveal fullerene binding affinities ( K a ) exceeding ≥10 6 M −1 . The size complementarity between fullerenes and these scaffolds maximizes CH⋯π and π⋯π interactions, and their host:guest adduct resembles a ball in a glove, hence their name as nanogloves. Fullerene recognition is tested by suspending carbon soot in a solution of nanoglove in 1,1,2,2‐tetrachloroethane, where more than a dozen fullerenes are observed, ranging from C 60 to C 96 .

  PublisherOA PDFDOI

• Exciton Trapping at Shape‐Persistent Molecular Nanotubes

  Angewandte Chemie · 2025-07-31

  articleSenior authorCorresponding

  Abstract We report a series of shape‐persistent molecular nanotubes with top rim connectivity traversing from an all‐ meta ‐ ( m 4 ) to an all‐ para ‐phenylene ( p 4 ) bridged species, including all possible members in between them. Single‐crystal X‐ray diffraction (SCXRD) and microcrystal electron diffraction (MicroED) data show a large torsional angle for meta ‐phenylenes relative to para ‐phenylene rings. Density functional theory (DFT) calculations reproduce the experimental torsional angles and also establish a correlation indicating a gradual increase in strain energy from m 4 (∼31 kcal mol −1 ) to p 4 (∼90 kcal mol −1 ). Structural transitions from m 4 to p 4 lead to additional correlations such as a shift in the lowest absorption wavelength from 330 to 394 nm, a sizeable red shift in the maximum emission wavelength from 444 to 546 nm, and a decrease in fluorescence quantum yield from 0.76 to 0.20, respectively. Time‐dependent (TD)‐DFT analysis of the relaxed excited state (S 1’ ) geometry shows a progression of exciton delocalization as para ‐phenylenes are introduced into m 4 en route to p 4 , while the overall molecular size remains constant. This effect is directly related to increased π‐conjugation within the nanotube's top‐segment and demonstrates how exciton trapping can take place without changing the nanotube's physical size, e.g., diameter and length.

  PublisherDOI

• Exciton Trapping at Shape‐Persistent Molecular Nanotubes

  Angewandte Chemie International Edition · 2025-07-31 · 5 citations

  articleSenior authorCorresponding

  Abstract We report a series of shape‐persistent molecular nanotubes with top rim connectivity traversing from an all‐ meta ‐ ( m 4 ) to an all‐ para ‐phenylene ( p 4 ) bridged species, including all possible members in between them. Single‐crystal X‐ray diffraction (SCXRD) and microcrystal electron diffraction (MicroED) data show a large torsional angle for meta ‐phenylenes relative to para ‐phenylene rings. Density functional theory (DFT) calculations reproduce the experimental torsional angles and also establish a correlation indicating a gradual increase in strain energy from m 4 (∼31 kcal mol −1 ) to p 4 (∼90 kcal mol −1 ). Structural transitions from m 4 to p 4 lead to additional correlations such as a shift in the lowest absorption wavelength from 330 to 394 nm, a sizeable red shift in the maximum emission wavelength from 444 to 546 nm, and a decrease in fluorescence quantum yield from 0.76 to 0.20, respectively. Time‐dependent (TD)‐DFT analysis of the relaxed excited state (S 1’ ) geometry shows a progression of exciton delocalization as para ‐phenylenes are introduced into m 4 en route to p 4 , while the overall molecular size remains constant. This effect is directly related to increased π‐conjugation within the nanotube's top‐segment and demonstrates how exciton trapping can take place without changing the nanotube's physical size, e.g., diameter and length.

  PublisherDOI

• Supramolecular inorganic chemistry: from form to function

  Supramolecular chemistry · 2025-05-30 · 1 citations

  articleOpen access

  The National American Chemical Society meetings bring together over 10,000 chemists spanning different nationalities and different sub-disciplines.During the Spring 2025 meeting in San Diego, CA, the corresponding authors organized a symposium called, "Supramolecular Inorganic Chemistry: From Form to Function."This symposium leveraged the broad attendance of the National ACS meeting to bring together supramolecular chemists in different research areas, highlighting the role of inorganic chemistry to address problems in catalysis, energy, sensing, and health.This manuscript provides the perspectives of the organizers of this symposium, as well as several presenters, on the up-and-coming areas of importance in the field of supramolecular inorganic chemistry.

  PublisherOA PDFDOI

• Disentangling the noncovalent interactions that drive metal cluster dimerization

  ChemRxiv · 2025-06-23

  preprintOpen access

  Understanding the atomistic interactions that drive self-assembly is a fundamental topic of broad interest in the design of supramolecular materials. The involvement of transition metal centers substantially enhances the number and types of interactions available in synthesizing designer chemical aggregates. In this work, we experimentally isolate supramolecular dimeric clusters of tetranuclear coinage metal (Cu, Ag, Au) monomers in the solid-state that adopt a cofacial [M4]–[M4] arrangement and exhibit short metal-metal distances and close M···H-C contacts. Through quantum chemical investigations – including Atoms-in-Molecules (AIM), Non-Covalent Interaction (NCI), and local energy decomposition (LED) analysis, along with proton NMR chemical shift calculations – we establish the existence of anagostic (and metallophilic) interactions that increase in strength going from Cu to Ag to Au. We proceed to quantify the relative contributions of various interactions to the observed dimerization. We find that multiple individually weak but cumulatively significant non-covalent interactions drive dimerization, with inter-ligand dispersion the most prominent (24-34 kcal/mol), followed by hydrogen bonding; metallophilic and anagostic interactions contribute 2-9 and 2-6 kcal/mol, respectively. Taken together, we establish that myriad non-covalent interactions can synergistically guide the precise formation of strongly bound coinage- metal dimers.

  PublisherOA PDFDOI

Frequent coauthors

• Saber Mirzaei

  University of Pittsburgh

  66 shared

• Theodore A. Betley

  Harvard University

  45 shared

• Colin Nuckolls

  Columbia University

  26 shared

• Shao‐Liang Zheng

  Harvard University

  24 shared

• Michael L. Steigerwald

  Columbia University

  20 shared

• Edison Arley Castro Portillo

  19 shared

• Manasseh Kusi Osei

  Rice University

  19 shared

• Edison Castro

  The University of Texas at El Paso

  18 shared

Labs

• Hernandez Sanchez Research GroupPI

  nanoscale materials synthesis at the interface between inorganic and materials chemistry

Education

• Ph.D. in Chemistry, Chemistry and Chemical Biology

  Harvard University

  2015

• A.M. in Chemistry, Chemistry and Chemical Biology

  Harvard University

  2012

• B.S. in Chemistry

  Instituto Tecnologico y de Estudios Superiores de Monterrey Campus Monterrey

  2010

Awards & honors

• Norman Hackerman Welch Young Investigator Junior Chair