The two-dimensional organic covalent framework material $\mathrm{TzDa-COF}$ can be synthesized by the condensation of **Tz** and **Da** (structures shown below), and it exhibits selective adsorption capabilities for acidic solutions containing $\mathrm{AuCl_4^-}$.  

<MultiModal>![The structural formula of **Tz** is C1=C(C=CC(=C1)N)C2=NC(=NC(=N2)C3=CC=C(C=C3)N)C4=CC=C(C=C4)N, and the structural formula of **Da** is C1=C(C(=CC(=C1C=O)O)C=O)O).](/media/uploads/574e547c-75f9-4d10-9a61-3cf5da201816.png)</MultiModal>  

The following options provide possible explanations based on experimental characterization results. Select the correct and reasonable statement(s).
二维有机共价框架材料$\mathrm{TzDa-COF}$可由**Tz**和 **Da**（二者结构见下图）缩合得到，其可以对含$\mathrm{AuCl_4^-}$的酸性溶液进行选择性吸附。

<MultiModal>![**Tz**的结构式为C1=C(C=CC(=C1)N)C2=NC(=NC(=N2)C3=CC=C(C=C3)N)C4=CC=C(C=C4)N，**Da**的结构式为C1=C(C(=CC(=C1C=O)O)C=O)O)。](/media/uploads/574e547c-75f9-4d10-9a61-3cf5da201816.png)</MultiModal>

下列选项中给出了根据实验得到的表征结果给出的可能解释，从中选出正确合理的说法。
Ideally, the stoichiometric ratio of **Tz** to **Da** required for the reaction is 3 : 2.
After the binding of $\mathrm{AuCl_4^-}$ to $\mathrm{TzDa-COF}$, the $\mathrm{1s}$ X-ray photoelectron spectroscopy of $\mathrm{N}$ did not show any peak corresponding to the binding energy of the $\mathrm{N-Au}$ bond. Only two peaks were observed: one corresponding to imine $\mathrm{N}$ and the other to the $\mathrm{N-H}$ bond.  

The absence of the $\mathrm{N-Au}$ bond indicates that $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ cannot combine through coordination interactions.
After adsorption is completed, Zeta potential measurements indicate that the $\mathrm{COF}$ material framework carries a negative charge. This result supports that the binding between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily driven by electrostatic interactions.
Infrared spectroscopy indicates that as the adsorption process proceeds, a new stretching vibration peak appears at $\mathrm{1668 cm^{-1}}$, and the peak area gradually increases. This stretching vibration peak corresponds to the carbonyl stretching vibration peak.
Under the condition of pH > 1, the adsorption capacity of $\mathrm{TzDa-COF}$ material for $\mathrm{AuCl_4^-}$ decreases with decreasing acidity. This result supports that the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily dominated by electrostatic forces.
As the concentration of $\mathrm{AuCl_4^-}$ in the solution increases, the adsorption capacity first rises and then tends to stabilize. This result may be attributed to the saturation of bonding sites on the $\mathrm{COF}$ surface, supporting that the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily coordination-based.
The $\mathrm{4f}$ X-ray photoelectron spectrum of $\mathrm{Au}$ indicates that after reacting the $\mathrm{AuCl_4^-}$-containing solution with $\mathrm{TzDa-COF}$ for 120 min, the binding energy of $\mathrm{4f}$ electrons of $\mathrm{Au}$ decreases compared to the initial state. If the reaction proceeds for 24 h, the binding energy increases compared to that at 120 min. The changes in binding energy suggest that the oxidation state of $\mathrm{Au}$ during the reaction may be +3, +1, or +2.
In the presence of 100 equivalents (large excess) of anions such as $\mathrm{NO}_{3}^{-}$, $\mathrm{SO}_{4}^{2-}$, $\mathrm{Cl}^{-}$, $\mathrm{PO}_{4}^{3-}$, $\mathrm{TzDa-COF}$ exhibits extremely high adsorption selectivity for $\mathrm{AuCl_4^-}$, indicating that the binding between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily electrostatic in nature.
In the presence of ions such as $\mathrm{Cu^{2+}}$ and $\mathrm{Ni^{2+}}$, $\mathrm{TzDa-COF}$ also exhibits extremely high adsorption selectivity for $\mathrm{AuCl_4^-}$, indicating that the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily based on coordination bonding.
None of the above options is correct.
理想情况下反应所需**Tz**和**Da**的计量比为3 : 2。
$\mathrm{TzDa-COF}$在结合$\mathrm{AuCl_4^-}$后,$\mathrm{N}$的$\mathrm{1s}$ X射线光电子能谱未观察到结合能符合$\mathrm{N-Au}$键的峰,仅得到了两个峰,一个对应亚胺$\mathrm{N}$,一个对应$\mathrm{N-H}$键。

无$\mathrm{N-Au}$键说明$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间不能以配位作用结合。
在完成吸附后, Zeta 电势测定表明 $\mathrm{COF}$ 材料骨架带有负电，该结果支持$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以静电作用结合。
红外光谱表明,随着吸附过程进行,$\mathrm{1668 cm^{-1}}$处新出现了一个伸缩振动峰,且峰面积逐渐变大，该伸缩振动峰对应于羰基的伸缩振动峰。
在pH>1的条件下$\mathrm{TzDa-COF}$材料对$\mathrm{AuCl_4^-}$的吸附量随酸度降低而减小，该结果支持$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以静电作用结合。
随溶液中$\mathrm{AuCl_4^-}$的浓度增大，吸附量亦先增大、后趋于不变，该结果可能是由于$\mathrm{COF}$表面成键饱和、支持$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以配位作用结合。
$\mathrm{Au}$的$\mathrm{4f}$ X射线光电子能谱表明，在将含$\mathrm{AuCl_4^-}$溶液与$\mathrm{TzDa-COF}$反应120 min后，$\mathrm{Au}$的$\mathrm{4f}$电子结合能相较于初始状态有所下降，若反应24 h，电子结合能又相较120 min时有所上升，结合能的变化说明$\mathrm{Au}$在反应过程中氧化态可能为+3、+1、+2。
在 100 当量(大大过量) $\mathrm{NO}_{3}^{-} 、 \mathrm{SO}_{4}{ }^{2-} 、 \mathrm{Cl}^{-} 、 \mathrm{PO}_{4}{ }^{3-}$ 等阴离子的存在下,$\mathrm{TzDa-COF}$对 $\mathrm{AuCl_4^-}$有极高的吸附选择性，这说明$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以静电作用结合。
在有$\mathrm{Cu^{2+} 、 Ni^{2+}}$ 等离子的存在下, $\mathrm{TzDa-COF}$对$\mathrm{AuCl_4^-}$同样有极高的吸附选择性，这说明$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以配位作用结合。
以上选项均不正确。
During the preparation of $\mathrm{TzDa-COF}$, the primary reaction is the condensation between the amino group of **Tz** and the aldehyde group of **Da**. Since **Tz** has a functionality of 3 and **Da** has a functionality of 2, the ideal stoichiometric ratio between them is 2:3, making option A incorrect.

<Checkpoint>[Under ideal conditions, the stoichiometric ratio of **Tz** to **Da** is 2:3](1)</Checkpoint>

For option B, X-ray photoelectron spectroscopy results only indicate that $\mathrm{Au}$ does not coordinate with $\mathrm{N}$. However, the $\mathrm{TzDa-COF}$ structure also contains $\mathrm{O}$ atoms capable of coordination, so the coordination mechanism cannot be ruled out. Thus, option B is incorrect.

<Checkpoint>[$\mathrm{O}$ atoms may participate in coordination, so the coordination mechanism cannot be excluded](1)</Checkpoint>

For option C, Zeta potential reflects the intrinsic charge of the material's framework. Under acidic conditions, the $\mathrm{N}$ atoms in the $\mathrm{TzDa-COF}$ framework are protonated, giving the system a positive charge. Therefore, if the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily electrostatic, the Zeta potential cannot be negative, making option C incorrect.

<Checkpoint>[The $\mathrm{N}$ atoms in the $\mathrm{TzDa-COF}$ framework are protonated, giving the system a positive charge](1)</Checkpoint>

<Checkpoint>[If the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is primarily electrostatic, the Zeta potential cannot be negative](1)</Checkpoint>

For option D, the new infrared absorption peak cannot originate from imine groups. At this wavenumber, only the formation of carbonyl groups (i.e., $\mathrm{Au(III)}$ undergoes redox with the hydroquinone segments in the material to yield a quinoid structure) can be considered, making option D correct.

<Checkpoint>[$\mathrm{Au(III)}$ undergoes redox with the hydroquinone segments in the material to yield a quinoid structure](1)</Checkpoint>

<Checkpoint>[The infrared spectrum indicates the formation of carbonyl groups](1)</Checkpoint>

For option E, as acidity increases, the degree of protonation of $\mathrm{N}$ atoms in the $\mathrm{TzDa-COF}$ framework decreases, which is unfavorable for electrostatic interaction with the negatively charged $\mathrm{AuCl_4^-}$. Additionally, higher acidity increases the hydrolysis of $\mathrm{AuCl_4^-}$, further reducing adsorption. Thus, the exact mechanism cannot be determined, making option E incorrect.

<Checkpoint>[As acidity increases, the protonation degree of $\mathrm{N}$ atoms in the $\mathrm{TzDa-COF}$ framework decreases, weakening electrostatic interaction](1)</Checkpoint>

<Checkpoint>[As acidity increases, the hydrolysis of $\mathrm{AuCl_4^-}$ intensifies, also reducing adsorption](1)</Checkpoint>

Option F is consistent with both electrostatic and coordination mechanisms, as both would exhibit adsorption saturation. Therefore, the mechanism cannot be determined, making option F incorrect.

<Checkpoint>[Both electrostatic and coordination mechanisms would exhibit adsorption saturation](1)</Checkpoint>

For option G, lower binding energy corresponds to a higher oxidation state of $\mathrm{Au}$. However, +2 is not a stable oxidation state for $\mathrm{Au}$; the plausible states are +3, 0, and +1, making option G incorrect.

<Checkpoint>[The oxidation states of $\mathrm{Au}$ during the reaction should be +3, 0, and +1](1)</Checkpoint>

For option H, the high adsorption selectivity for $\mathrm{AuCl_4^-}$ in the presence of other abundant anions without competition suggests that the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is not electrostatic, making option H incorrect.

<Checkpoint>[No competition from other anions indicates the interaction between $\mathrm{TzDa-COF}$ and $\mathrm{AuCl_4^-}$ is not electrostatic](1)</Checkpoint>

For option I, the high adsorption selectivity in the presence of other metal cations (e.g., $\mathrm{Cu^{2+}, Ni^{2+}}$) does not exclude the electrostatic mechanism. Since $\mathrm{AuCl_4^-}$ is negatively charged while $\mathrm{Cu^{2+}, Ni^{2+}}$ are positively charged, electrostatic repulsion between the cations and the framework could prevent their adsorption, making option I incorrect.

<Checkpoint>[In the presence of $\mathrm{Cu^{2+}, Ni^{2+}}$, electrostatic repulsion may prevent their adsorption, so the electrostatic mechanism cannot be excluded](1)</Checkpoint>

Thus, option D is correct.
在$\mathrm{TzDa-COF}$的制备过程中主要发生**Tz**的氨基与**Da**的醛基之间的缩合，而**Tz**的官能度为3、Da的官能度为2，因此理想情况下二者计量比为2 : 3，选项A错误。

<Checkpoint>[理想情况下**Tz**和**Da**的计量比为2 : 3](1)</Checkpoint>

对于选项B，X射线光电子能谱的结果只能说明$\mathrm{Au}$没有和$\mathrm{N}$配位，而$\mathrm{TzDa-COF}$结构中还有可参与配位的$\mathrm{O}$原子，因此不能排除配位机理，选项B错误。

<Checkpoint>[还可能是$\mathrm{O}$原子参与配位，不能排除配位机理](1)</Checkpoint>

对于选项C，Zeta电势反映的是材料骨架本身所带的电荷，而酸性条件下$\mathrm{TzDa-COF}$骨架中的$\mathrm{N}$原子会被质子化使体系带正电，因此如果$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以静电作用结合，Zeta电势不可能为负，选项错误。

<Checkpoint>[$\mathrm{TzDa-COF}$骨架中的$\mathrm{N}$原子会被质子化使体系带正电](1)</Checkpoint>

<Checkpoint>[如果$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间主要以静电作用结合，Zeta电势不可能为负](1)</Checkpoint>

对于选项D，红外光谱峰是新出现的，因此不可能来自于亚胺，在该波数处只能考虑羰基的形成（即$\mathrm{Au(III)}$和材料中的对苯二酚片段发生了氧化还原得到醌式结构），选项正确。

<Checkpoint>[$\mathrm{Au(III)}$和材料中的对苯二酚片段发生了氧化还原得到醌式结构](1)</Checkpoint>

<Checkpoint>[红外光谱表明了羰基的形成](1)</Checkpoint>

对于选项E，随酸度升高，$\mathrm{TzDa-COF}$骨架中的$\mathrm{N}$原子被质子化的程度减小，这会不利于骨架与带负电荷的$\mathrm{AuCl_4^-}$之间以静电作用结合。但随酸度升高，$\mathrm{AuCl_4^-}$的水解程度也加大，这也会降低吸附量，因此无法判断准确机理，选项错误。

<Checkpoint>[随酸度升高，$\mathrm{TzDa-COF}$骨架中的$\mathrm{N}$原子被质子化的程度减小，不利于静电作用](1)</Checkpoint>

<Checkpoint>[随酸度升高，$\mathrm{AuCl_4^-}$的水解程度也加大，这也会降低吸附量](1)</Checkpoint>

选项F对静电作用机理和配位作用机理均满足，二者都会出现吸附饱和现象，无法判断，选项错误。

<Checkpoint>[静电作用机理和配位作用机理都会出现吸附饱和现象](1)</Checkpoint>

对于选项G，结合能越低，$\mathrm{Au}$的氧化态越高，但是+2价并非$\mathrm{Au}$的稳定氧化态，更合理的应该是+3、0、+1，选项错误。

<Checkpoint>[$\mathrm{Au}$在反应过程中氧化态应为+3、0、+1](1)</Checkpoint>

对于选项H，在体系中含有其它种类且大过量的阴离子时仍有高吸附选择性，未发生竞争，说明$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间不是以静电作用结合，选项错误。

<Checkpoint>[其它阴离子未发生竞争，说明$\mathrm{TzDa-COF}$和$\mathrm{AuCl_4^-}$之间不是以静电作用结合](1)</Checkpoint>

对于选项I，其它金属阳离子共存情况下的高吸附选择性不能排除静电机理，因为$\mathrm{AuCl_4^-}$带负电而$\mathrm{Cu^{2+} 、 Ni^{2+}}$带正电，若为静电机理，可能正电离子与骨架有电荷排斥、无法有效吸附，选项错误。

<Checkpoint>[在有$\mathrm{Cu^{2+} 、 Ni^{2+}}$等离子共存的情况下，可能正电离子与骨架有电荷排斥、无法有效吸附，因此无法排除静电机理](1)</Checkpoint>

因此，选项D正确。