Houston Daily

A research team at the University of Houston has developed a new method to bend and twist crystals without using physical force, heat, or radiation. The study, led by Jeffrey Rimer, Abraham E. Dukler Professor of Chemical Energy, demonstrates how a molecule called a tautomer can induce these changes in biogenic crystals.

Tautomers are molecules that can rearrange their atoms, causing hydrogen atoms and others to shift positions. This property allows them to influence the formation and shape of crystals. Rimer explained that this process could have significant implications for drug delivery because about 30 of the top 200 drugs are tautomers.

“Here, we present a unique case of natural bending without the application of external forces,” said Rimer in the journal PNAS.

The research was conducted at The Welch Center for Advanced Bioactive Materials Crystallization at UH. “This is a mechanistic investigation showing how tautomerism induces controlled, natural bending and twisting by virtue of the minor tautomer, which is a growth modifier that causes defects in the crystal structure (e.g., twins, screw and edge dislocations), leading to macroscopic effects on material properties,” Rimer stated.

Material flexibility through phenomena such as bending and twisting molecular crystals is drawing more attention due to its potential applications in fields like optoelectronics, soft robotics, smart sensors, and pharmaceuticals. According to Rimer, “We have shown that bending leads to physical deformations that impact dissolution, which can impact pharmacokinetics in the delivery of active pharmaceutical ingredients.”

The degree of curvature achieved by this method can be adjusted by changing growth conditions. Advanced microscopy and spectroscopy techniques were used to analyze how bending occurs at the microscopic level.

“Our findings provide a greater understanding of the defects generated during pathological crystallization of a tautomeric material and how this phenomenon can lead to unique bent, twisted, and dendritic morphologies observed in both biological and synthetic materials,” said Rimer. “The ability to selectively control this behavior opens broad avenues for crystal engineering.”

Other contributors include Weiwei Tang and Francisco Robles Hernandez from UH; Tamin Yang from Stockholm University; Qing Tu from Texas A&M University; Hector Calderone from Instituto Politecnico Nacional in Mexico; along with researchers from Molecular Vista Inc.

The Welch Center for Advanced Bioactive Materials Crystallization was founded at UH in 2023 with $5 million funding from the Welch Foundation. The center aims to promote progress in fundamental chemical research across Texas institutions. It recently hosted an industrial advisory board meeting with representatives from eight major pharmaceutical companies as well as a summer camp focused on crystallization for high school and undergraduate students.