A Theoretical Investigation of Two Typical Two‐Photon pH Fluorescent Probes

Leng

2018

Sensors

In the present work, we systematically investigate the sensing abilities of two recently literature-reported two-photon fluorescent NO probes, i.e., the o-phenylenediamine derivative of Nile Red and the p-phenylenediamine derivative of coumarin. The recognition mechanisms of these probes are studied by using the molecular orbital classifying method, which demonstrates the photoinduced electron transfer process. In addition, we have designed two new probes by swapping receptor units present on fluorophores, i.e., the p-phenylenediamine derivative of Nile Red and the o-phenylenediamine derivative of coumarin. However, it illustrates that only the latter has ability to function as off-on typed fluorescent probe for NO. More importantly, calculations on the two-photon absorption properties of the probes demonstrate that both receptor derivatives of coumarin possess larger TPA cross-sections than Nile Red derivatives, which makes a better two photon fluorescent probe. Our theoretical investigations reveal that the underlying mechanism satisfactorily explain the experimental results, providing a theoretical basis on the structure-property relationships which is beneficial to developing new two-photon fluorescent probes for NO.

Section: Resultsmentioning

confidence: 99%

Theoretical Design of a Two-Photon Fluorescent Probe for Nitric Oxide with Enhanced Emission Induced by Photoninduced Electron Transfer

Leng

2018

Sensors

“…One can expect the different TPA performances of Pro1 and Pro2 are due to their different spacers. Herein, we analyze the TPA cross-sections of the two probes by a two-level model with the ground state and the maximum charge transfer state [ 37 ] according to the transition natures of the probes as shown in Table 1 . In this model, the peak TPA cross-section is directly proportional to the square of the transition dipole moment μ 01 , while inversely proportional to the square of the energy gap Ε 01 , namely, σ TPA ∝ μ 01 2 / Ε 01 2 .…”

Section: Resultsmentioning

confidence: 99%

Theoretical Studies on Two-Photon Fluorescent Hg2+ Probes Based on the Coumarin-Rhodamine System

Leng

2017

Sensors

The development of fluorescent sensors for Hg2+ has attracted much attention due to the well-known adverse effects of mercury on biological health. In the present work, the optical properties of two newly-synthesized Hg2+ chemosensors based on the coumarin-rhodamine system (named Pro1 and Pro2) were systematically investigated using time-dependent density functional theory. It is shown that Pro1 and Pro2 are effective ratiometric fluorescent Hg2+ probes, which recognize Hg2+ by Förster resonance energy transfer and through bond energy transfer mechanisms, respectively. To further understand the mechanisms of the two probes, we have developed an approach to predict the energy transfer rate between the donor and acceptor. Using this approach, it can be inferred that Pro1 has a six times higher energy transfer rate than Pro2. Thus the influence of spacer group between the donor and acceptor on the sensing performance of the probe is demonstrated. Specifically, two-photon absorption properties of these two probes are calculated. We have found that both probes show significant two-photon responses in the near-infrared light region. However, only the maximum two-photon absorption cross section of Pro1 is greatly enhanced with the presence of Hg2+, indicating that Pro1 can act as a potential two-photon excited fluorescent probe for Hg2+. The theoretical investigations would be helpful to build a relationship between the structure and the optical properties of the probes, providing information on the design of efficient two-photon fluorescent sensors that can be used for biological imaging of Hg2+ in vivo.

“…One can expect that different TPA performances of Pro1, Pro2 and Pro3 are attributed to their different donors. Herein, we analyze TPA cross sections of donors of Pro1 (Pro1‐Donor), Pro2 (Pro2‐Donor) and Pro3 (Pro3‐Donor) by two‐level model with the ground state

S_{0}

and the charge transfer state

S_{1}

{italicσ}_{normaltpa} \propto \frac{{italicμ}_{01}^{2} Δ {italicμ}^{2}}{E_{01}^{2} Γ},

where

μ_{01}

and

Δ μ

are the transition dipole moment and dipole moment difference between

S_{0}

and

S_{1}

, respectively, and

E_{01}

donates the excitation energy of

S_{1}

. The damping factor

normalΓ

is set to 0.1 eV.…”

Section: Resultsmentioning

confidence: 99%

Influence of Donor on the Sensing Performance of a Series of Through‐Bond Energy Transfer‐Based Two‐photon Fluorescent Cu²⁺ Probes

Photochem & Photobiology

Wang

Zhou

et al. 2016

Optical properties of a series of molecular two-photon fluorescent Cu(2+) probes containing the same acceptor (rhodamine group) are analyzed using time-dependent density functional theory in combination with analytical response theory. Special emphasis is placed on evolution of the probes' optical properties in the presence of Cu(2+) . In this study, the compound with naphthalene as the donor is shown to be excellent ratiometric fluorescent chemosensor, whereas the compound with quinoline derivative as the donor shows off/on-typed colorimetric fluorescent response. For the compound with naphthalimide derivative as the donor, changing the connection between the donor and acceptor can efficiently prevent the fluorescent quenching of the probe both in the absence and presence of Cu(2+) . The donor moiety and the connection between donor and acceptor are thus found to play dominant roles on sensing performance of these probes. Moreover, distributions of molecular orbitals involved in the excitation and emission of the probes are analyzed to explore responsive mechanism of the probes. The through-bond energy transfer process is theoretically demonstrated. Our results are used to elucidate the available experimental measurements. This work is helpful to understand the relationships of structure with optical properties for the studied probes.