Zhang Depeng, Yang Xinrui, Jiang Wanrun, Jin Le, Gao Yi, Wang Zhigang
Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
ACS Nano. 2021 Feb 23;15(2):2490-2496. doi: 10.1021/acsnano.0c06508. Epub 2021 Jan 20.
Water is ubiquitous on Earth and dominates chemical and biological processes in daily life. However, how water behaves under some critical conditions is not fully understood. In this paper, we employed quantum first-principles calculations and dynamics simulations to reveal the unexpectedly high mobility of water molecules in ultraconfined spaces. The water molecules rotated more freely in the (4, 4) carbon nanotube than in the (5, 5) carbon nanotube, which is induced by the Pauli repulsion from the wall of the narrower channel when reducing the size of the channel from general confinement to ultraconfinement. Moreover, this quantum effect facilitates the transport of water molecules into the space within their van der Waals diameter easily, which is in contrast to the general understanding. Thus, the conventional concept that the tighter the confined space, the more difficult the motion of the confined object is not always correct. This quantum-induced enhancement of water mobility by Pauli repulsion calls us to pay more attention to the existence and the function of water in neglected ultraconfined spaces (.., cells and the Earth's crust) in the future.
水在地球上无处不在，主导着日常生活中的化学和生物过程。然而，在某些临界条件下水的行为尚未得到充分理解。在本文中，我们采用量子第一性原理计算和动力学模拟来揭示水分子在超受限空间中出人意料的高迁移率。水分子在（4,4）碳纳米管中比在（5,5）碳纳米管中旋转得更自由，这是在将通道尺寸从一般受限减小到超受限时，由较窄通道壁的泡利排斥所引起的。此外，这种量子效应有助于水分子轻松地进入其范德华直径范围内的空间，这与一般认知相反。因此，传统观念认为受限空间越紧密，受限物体的运动就越困难，这并不总是正确的。这种由泡利排斥引起的量子诱导的水迁移率增强促使我们在未来更加关注被忽视的超受限空间（如细胞和地壳）中水的存在和功能。
